Hi and welcome,
Could you attach the Crash/DMP file, please?
Mac: macOS Console utility > User Reports folder (or ~user/Library/Logs/Diagnostic Reports).
Win: Documents/Steinberg/Crash Dumps
You can also share the link via Dropbox or similar service.
Could you try in Cubase Safe Start Mode [Disable preferences], please?
Btw, By default, MediaBay opens when you hit F5. F7 is for the Direct Offline Process window.