diff --git a/src/blenderbim/blenderbim/bim/module/sequence/operator.py b/src/blenderbim/blenderbim/bim/module/sequence/operator.py
index 60c4dd2e1d..a591f47b77 100644
--- a/src/blenderbim/blenderbim/bim/module/sequence/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/sequence/operator.py
@@ -575,7 +575,7 @@ class AssignPredecessor(bpy.types.Operator):
             "sequence.edit_sequence", self.file, rel_sequence=rel, attributes={"SequenceType": "FINISH_START"}
         )
         Data.load(self.file)
-        bpy.ops.bim.load_task_properties(task=self.task)
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -597,7 +597,7 @@ class AssignSuccessor(bpy.types.Operator):
             "sequence.edit_sequence", self.file, rel_sequence=rel, attributes={"SequenceType": "FINISH_START"}
         )
         Data.load(self.file)
-        bpy.ops.bim.load_task_properties(task=self.task)
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -616,7 +616,7 @@ class UnassignPredecessor(bpy.types.Operator):
             related_process=IfcStore.get_file().by_id(props.active_task_id),
         )
         Data.load(self.file)
-        bpy.ops.bim.load_task_properties(task=self.task)
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -635,7 +635,7 @@ class UnassignSuccessor(bpy.types.Operator):
             related_process=self.file.by_id(self.task),
         )
         Data.load(self.file)
-        bpy.ops.bim.load_task_properties(task=self.task)
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -1166,19 +1166,18 @@ class EditTaskCalendar(bpy.types.Operator):
 
     def execute(self, context):
         self.file = IfcStore.get_file()
+        task = self.file.by_id(self.task)
         ifcopenshell.api.run(
             "control.assign_control",
             self.file,
             **{
                 "relating_control": self.file.by_id(self.work_calendar),
-                "related_object": self.file.by_id(self.task),
+                "related_object": task,
             },
         )
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
         Data.load(IfcStore.get_file())
-        if Data.tasks[self.task]["RelatedObjects"]:
-            bpy.ops.bim.load_task_properties()
-        else:
-            bpy.ops.bim.load_task_properties(task=self.task)
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -1190,19 +1189,18 @@ class RemoveTaskCalendar(bpy.types.Operator):
 
     def execute(self, context):
         self.file = IfcStore.get_file()
+        task = self.file.by_id(self.task)
         ifcopenshell.api.run(
             "control.unassign_control",
             self.file,
             **{
                 "relating_control": self.file.by_id(self.work_calendar),
-                "related_object": self.file.by_id(self.task),
+                "related_object": task,
             },
         )
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
         Data.load(IfcStore.get_file())
-        if Data.tasks[self.task]["RelatedObjects"]:
-            bpy.ops.bim.load_task_properties()
-        else:
-            bpy.ops.bim.load_task_properties(task=self.task)
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -1294,6 +1292,7 @@ class UnassignLagTime(bpy.types.Operator):
             "sequence.unassign_lag_time", self.file, **{"rel_sequence": self.file.by_id(self.sequence)}
         )
         Data.load(IfcStore.get_file())
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -1328,6 +1327,7 @@ class EditSequenceAttributes(bpy.types.Operator):
         )
         Data.load(self.file)
         bpy.ops.bim.disable_editing_sequence()
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
@@ -1347,6 +1347,7 @@ class EditSequenceTimeLag(bpy.types.Operator):
         )
         Data.load(self.file)
         bpy.ops.bim.disable_editing_sequence()
+        bpy.ops.bim.load_task_properties()
         return {"FINISHED"}
 
 
diff --git a/src/blenderbim/blenderbim/bim/module/sequence/prop.py b/src/blenderbim/blenderbim/bim/module/sequence/prop.py
index 0363bf7c0b..9c75f55d24 100644
--- a/src/blenderbim/blenderbim/bim/module/sequence/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/sequence/prop.py
@@ -104,7 +104,7 @@ def updateTaskTimeDateTime(self, context, startfinish):
         **{"task_time": task_time, "attributes": {startfinish_key: startfinish_datetime}},
     )
     Data.load(IfcStore.get_file())
-    bpy.ops.bim.load_task_properties(task=props.active_task_id)
+    bpy.ops.bim.load_task_properties()
     setattr(self, startfinish, canonicalise_time(startfinish_datetime))
 
 
@@ -129,7 +129,7 @@ def updateTaskduration(self, context):
         attribute = props.task_time_attributes.get("Duration")
         if attribute:
             attribute.string_value = self.duration
-    bpy.ops.bim.load_task_properties(task=props.active_task_id)
+    bpy.ops.bim.load_task_properties()
 
 
 def updateVisualisationStart(self, context):
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
index 9e0d598dbd..46c13f924e 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
@@ -73,8 +73,6 @@ class Usecase:
                     finishes.append(self.offset_date(start, days, duration_type, self.get_calendar(predecessor)))
                 else:
                     finishes.append(start)
-            else:
-                return
 
         if starts and finishes:
             start = max(starts)
@@ -135,8 +133,6 @@ class Usecase:
                 ),
                 "IfcDateTime",
             )
-        else:
-            return
 
         for rel in task.IsPredecessorTo:
             self.cascade_task(rel.RelatedProcess)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_lag_time.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_lag_time.py
index e415b93be7..9089ab6bc1 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_lag_time.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_lag_time.py
@@ -1,3 +1,4 @@
+import ifcopenshell.api
 import ifcopenshell.util.date
 
 
@@ -16,3 +17,5 @@ class Usecase:
                 else:
                     value = self.file.createIfcDuration(ifcopenshell.util.date.datetime2ifc(value, "IfcDuration"))
             setattr(self.settings["lag_time"], name, value)
+        for rel in [r for r in self.file.get_inverse(self.settings["lag_time"]) if r.is_a("IfcRelSequence")]:
+            ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=rel.RelatedProcess)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_sequence.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_sequence.py
index b43c7c84a5..d11febfb00 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_sequence.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_sequence.py
@@ -1,3 +1,7 @@
+import ifcopenshell
+import ifcopenshell.api
+
+
 class Usecase:
     def __init__(self, file, **settings):
         self.file = file
@@ -8,3 +12,7 @@ class Usecase:
     def execute(self):
         for name, value in self.settings["attributes"].items():
             setattr(self.settings["rel_sequence"], name, value)
+        if "SequenceType" in self.settings["attributes"].keys():
+            ifcopenshell.api.run(
+                "sequence.cascade_schedule", self.file, task=self.settings["rel_sequence"].RelatedProcess
+            )
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_lag_time.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_lag_time.py
index 4654bac061..9cf40abec1 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_lag_time.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_lag_time.py
@@ -1,3 +1,6 @@
+import ifcopenshell.api
+
+
 class Usecase:
     def __init__(self, file, **settings):
         self.file = file
@@ -9,5 +12,9 @@ class Usecase:
 
     def execute(self):
         if len(self.file.get_inverse(self.settings["rel_sequence"].TimeLag)) == 1:
-            return self.file.remove(self.settings["rel_sequence"].TimeLag)
-        self.settings["rel_sequence"].TimeLag = None
+            self.file.remove(self.settings["rel_sequence"].TimeLag)
+        else:
+            self.settings["rel_sequence"].TimeLag = None
+        ifcopenshell.api.run(
+            "sequence.cascade_schedule", self.file, task=self.settings["rel_sequence"].RelatedProcess
+        )
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_sequence.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_sequence.py
index 496b8bfec2..fb1ffda88b 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_sequence.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/unassign_sequence.py
@@ -16,3 +16,4 @@ class Usecase:
         for rel in self.settings["related_process"].IsSuccessorFrom or []:
             if rel.RelatingProcess == self.settings["relating_process"]:
                 self.file.remove(rel)
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=self.settings["related_process"])