Pasting a metronome marking into a tempo marking box does not honour the metronome marking in playback BPM

Issue type

UX/Interaction bug (incorrect behaviour)

Description with steps to reproduce

1. Open a score.
2. Drag an 'Allegretto' tempo marking to the start. Playback speed shows that the tempo is 116 BPM.
3. Drag a MM80 metronome marking from the palette to the start. Playback speed now shows that the tempo is 80 BPM
4. Now double-click the metronome marking, select all and copy the marking. Delete the metronome marking
5. Double-click the 'Allegretto' marking, and paste the metronome marking in afterwards

Expected behaviour:
Playback speed should now be 80 BPM

Actual behaviour:
Playback speed remains at 116 BPM

Supporting files, videos and screenshots

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

4.5.2

Regression

I was unable to check

Operating system

macOS

Additional context

From a music typesetting point-of-view, it is preferable to have a (textual) tempo marking and a metronome marking incorporated into a single text object. Doing so ensures that spacing/kerning between text and MM do not change when the music is respaced, and gives us finer-grained control.

There are two suggestions here:

1. Add a fix so that metronome markings incorporated into a tempo object are honoured
2. Create a text object in the Tempo palette that incorporates both a word and a metronome marking, rather than splitting them out into two objects.

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

Start by reproducing the reported copy-and-paste sequence in MuseScore Studio and trace how tempo markings determine playback BPM. No source files, tests, or entry points are named in the issue; done means a pasted MM80 inside the Allegretto tempo object makes playback use 80 BPM, with coverage for that behavior.