[MU4 Issue] Playback not in sync with playhead when changing instrument in mixer

[bkunda]

Describe the bug
Note: similar to #14894, but with a different trigger

When substituting instruments in the mixer and then resuming playback mid-score, the substituted instrument alone recommences playback from the start of the score (concurrently with the playback at playhead position).

To Reproduce
See demo video:
https://www.dropbox.com/s/mx9ymh9rtbfihax/playback-sync-position-change.mov?dl=0

Expected behavior
Substituted instrument should not recommence playback from start, but should instead sync with current playhead position.

Platform information

• macOS 12.6 (M1)
• RC (4.0.0.223411003)

[pmarx810]

@Tantacrul @bkunda Very similar to #14902 , could be duplicate

[pmarx810]

@Tantacrul @MarcSabatella @RomanPudashkin also similar to the issue found in #14910

[bkunda]

Thanks @pmarx810, all these issues do indeed seem very similar to one another.
I'll keep this one open for now though because it contains a demo video, which is always useful for our devs so they can actually see what's going on.
Thanks!

[MarcSabatella]

@Tantacrul this one comes up often and I assume it would be a simple fix to consider for a patch

[cbjeukendrup]

@Tantacrul this one comes up often and I assume it would be a simple fix to consider for a patch

@Tantacrul This would indeed be good. Not sure how simple it is (although it can't be too complicated), but it would certainly be nice to get this fixed since it has come up quite a few times.

[Tantacrul]

I'd like to hear what @vpereverzev has to say.

Patch or 4.1?

[bkunda]

@DmitryArefiev can you please check this one again for validity/reproducibility?

[DmitryArefiev]

@bkunda Yes, still occurs (4.2 nightly master, MuseSounds, Win10).

Can't reproduce with MS Basic

[bkunda]

Also from #14894:

Steps to reproduce the behavior:

Play a score with the current instrument
Stop the playback, don't change position of the play head
Change instrument
Start playback.
Playback starts at the beginning of the score, while play head continues from current position somewhere in the score.

[DmitryArefiev]

Fixed in #20626