copy_cost_item appends the copy to the inverse relationships of the
original cost item, which for a root cost item includes the source
schedule's IfcRelAssignsToControl. copy_cost_schedule then assigned that
same cost item to the new schedule as well, so the copies showed up in
both schedules and deleting them from one removed them from the other.
Unassign the copy from the source schedule before assigning it to the
new one.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A feature allowing duplicate existing IfcCostSchedule - either from API or from Bonsai UI
Button location in Bonsai - https://files.catbox.moe/ct058q.png