Can't change time signature property before line break

Issue type

UX/Interaction bug (incorrect behaviour)

Description with steps to reproduce

Alternative title for searching:
Can't change time signature number / text at system end

Nothing in time signature property dialog works, if entering that dialog from the (courtesy?) time signature before system break; but it works if change from the "real" time signature in the next system.

Supporting files, videos and screenshots

The beam selector behaves the same, tested but not shown in GIF.

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

4.5.0, 4.5.1 and nightly 26th March

Regression

Yes, this used to work in MuseScore 3.x and now is broken

Operating system

Win11 24H2

Additional context

It was kinda working in MS3, because there's simply no property in context menu for the "fake" courtesy time signature before line break.

Discovered when testing 27382. No link on purpose, because I don't think this one's related to that one.
(Yes, style menu works from both time sigs)

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 issue in MuseScore using the reported time-signature property dialog at a system break, then compare it with the corresponding element in the next system. Check the behavior of the time signature and beam selector interactions described in the report. Done means the relevant properties can be changed from the courtesy element as well as from the following real element.