Have you modified any of the theme files or fonts? If so, there was another thread this morning that suggests that these changes might be causing issues. If you haven’t made any changes, I’d suggest moving your current Roon app to the desktop then downloading a fresh version from the link below. This won’t affect your database, it’s just replacing the app with a new version. When you’ve got everything working again, delete the old version from your desktop.
https://roonlabs.com/downloads
Alternatively, there’s a work-around solution here: