--export-score-parts / -P CLI options no longer work in 4.x

[ridgekuhn]

Issue type

Import/export issue

Bug description

In 4.x, after exporting a PDF from the command line and passing the -P or --export-score-parts option, the generated PDF does not contain individual parts, only the full score.

Steps to reproduce

mscore --export-score-parts --export-to ~/Desktop/test.pdf ~/test.mscz

Screenshots/Screen recordings

No response

MuseScore Version

4.x

Regression

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

Operating system

MacOS, Linux

Additional context

No response

[haklein]

Is there any way to export parts to PDF or SVG in 4.x per commandline? This worked perfectly fine in 3 e.g. via json jobs (see #19359), this is also broken in all 4.x releases.