Changing 4/4 time signature to 3/4 causes corruption

1. Create 4/4 piano score.
2. Drag 3/4 time signature onto first bar.

Expected result: The quantity of bars remains the same, with one rest per bar.
Actual result: The quantity of bars extend. Some bars have a combination of minim and crotchet rests. In the final bar; whilst the bass stave has three beats (with colliding rests), the treble stave only has two beats.

Using MuseScore 2.0 Nightly Build (5559) - Mac 10.7.3.