incorrect fonts used when system Qt version is 5.13 or higher
When running the latest stable or dev version of MuseScore on a Linux system featuring Qt version 5.13 or higher, fonts in MuseScore are not displayed correctly. I have verified this happens in both Manjaro (presumably also Arch) and KDE neon, which currently use Qt 5.13.0 and 5.13.1 respectively.
Here is what MuseScore looks like using Qt 5.12.3:
Here it is using Qt 5.13.1:
You can see the FreeSerif font is not being used, despite it being selected in style preferences. This does not affect the AppImage version of MuseScore, but does affect versions from the system repository (or Ubuntu/neon PPA) and compiled from source, including the latest git.