disabling multimeasure rests in parts doesn't "survive" save/close/reopen

1. Create new score with several instruments, e.g. using the SATB template
2. Generate parts ("all new")
3. Switch to one of the parts, e.g. Soprano
4. Press M to disable multimeasure rests
5. Verify that multimeasure rests are really disabled for this part, but still enabaled for the other parts
6. Save score
7. Close score
8. Open score
9. Check that part

Expected result: multimeasure rests are disabled
Actual result: multimeasure rests are enabled