Is Time Signature change broken in the trunk?

Most scores will not change from 4/4 to 3/4, or 3/4 to 4/4 without crashing.

When it does work, there's instances where ties will not move as new ones are created, but upon undo, the new ones don't disappear either.

I can't seem to find a reason - does anyone know why?

Using MuseScore 2.0 Nightly Build (4631) - Mac 10.6.8.