Problem with Hairpin playback

[rgreen5]

Issue type

General playback bug

Description with steps to reproduce

1. Open the attached MS 3.6.2 score
2. Play back the first few bars, 201-204
3. Notice the irregular volume (!) transition between hairpins

Supporting files, videos and screenshots

hairpin_playback_issue.zip

What is the latest version of MuseScore Studio where this issue is present?

MuseScore Studio version (64-bit): 4.4.0-242390800, revision: github-musescore-musescore-0fcd11b

Regression

Looks likely.

Operating system

OS: Linux Mint 20.1, Arch.: x86_64,

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible

[cbjeukendrup]

Copying relevant parts of the discussion at #24569 (comment): it seems that this is caused by the invisible dynamic markings (rather than the hairpins themselves); the dynamic markings are in voice 2, while the hairpins are set to affect all voices.
Given that this score is imported from a pre-4.4 version, this inconsistent voice assignment must have been the result of MuseScore 4.4's own import heuristic.

So, this issue has two parts:

1. We should improve the import heuristic, to produce more consistent results when both hairpins and dynamics are involved at the same location
2. We should improve the playback engine, so that it renders better results when a user intentionally creates such an "inconsistent" voice assignment.