Cubase 12 no waveform inside audioeditor

hey cubase friends,

i am using cubase 12, win10. latest updates installed.
since my last project cubase 12 dont display any waveform inside the audioeditor anymore. its black. no
matter which project i am my project window eveything display correctly. all the waveforms are there. but as soon as i
go to inside audioeditor. waveform
i rename the old setting folder to „cubase 12 old“ so that cubase can create a new by itself.
it works one time. as soon as i reopen the session again. waveform wont display anymore like before. in the audioeditor. if i open that same project or all my other projects it works fine. no any waveform display issues. any ideas?
thx in advance