Volta / Repeat Playback Skips Prima Volta and Plays Seconda Volta Twice

(Windows Vista, MuseScore V1.2 R5470)
In the attached MS file, when I drop an end repeat bar onto measure 12, numerous playback errors occur.
1. The first volta is skipped (it's never played by MS).
2. After the second volta plays, playback returns to measure 3, instead of playing measure 2.
3. The second volta is played twice, but during playback of measure 11, two notes are played, but there's only one note in measure 11.
4. Other errors occur, but I haven't listed them here.

You'll see that when you drop a normal bar onto measure 12, these errors disappear, but the music isn't played as desired.

The desired playback should be as follows:
A. Play measures 1-10.
B. Play measures 2-8 plus 11-12.
C. Play measures 2-8 plus 13-15.
D. Play measures 16-18 twice.
E. Play measures 19-23.
F. Play measures 5-7.
G. Play measures 24-26.