Changing measure length creates phantom measures

Version: 4.0.0
Platform: Windows 10

Description:
When editing a measure that already has notes in it to have more beats (including changing the tempo (eg from 7/4 to 15/8)) "phantom measures" get added instead of just adding to the measure selected. Further it looks like the measure that I selected gets "wider" by the correct amount, but no new rests are added.

Before:

After: