Missing waveform from MP3 in FCP 10.6.5
Working on video one day all is fine then waveforms gone on all MP3s. Still there for videos but not MP3s. Not corrupted files as they will play elsewhere. (Recently installed Ventura if that is. cause.)
Reboot the computer. Trash your library cache. Reopen the library and wait before doing anything for the content to rebuild. This is easiest done if the cache is external, otherwise you have to dig it out of the library bundle careful.
P.S. Convert MP3s to WAV or AIF.