Playback desync across repeat

I have installed MS4.0 release and have found a playback desync issue.
Here's how it happens:
1. I installed Muse Strings and Muse Keys only
2. Opened the score
3. Turned off "play repeats"
4. Started playback just before the end repeat sign
5. Continued after it, as expected.
6. WITHOUT PAUSING, I turned on "play repeats"
7. The score then jumps back to near the start of the repeat, and only the strings are aligned with the playhead. The winds, brass, and timpani are slightly behind. My theory is that they're playing from the start of the piece rather than the start repeat. I suspect this has something to do with Muse Sounds, as only the strings are at the right time.