Channel changes after adding a channel change text is not synced between part and score

Special steps to reproduce:
1. Create a score with for example Trombone
2. Add few notes
3. Add new single part for trombone (order is important, if done later, situation is different)
4. From main part: Add custom staff text (CTRL-T) to first note. For instance Cup Mute
5. Change Staff Text properties to switch to mute channel for voices 1,2,3,4
6. Switch over to part Trombone.
7. Inspect the staff text properties. They are unchanged (still open channel).

Also the reverse does not sync back. When changing staff text properties on the part it is not synced back to the main part. Only channel switches from main part are used.

Workaround is to set staff text properties on both central and trombone part. Other workaround is to add trombone part later (after changing the staff text properties)