This was driving me a bit crazy. Had major audio waveform issues in several projects both big and small. After many attempts and searching online, finally found this article
https://forums.adobe.com/thread/2152942
Basically, go to preferences in Premiere Pro CC. Make sure you are pointed to the following locations. If it asks you to move or delete the database, choose “delete”.
Mac: /Users//Library/Application Support/Adobe/Common
Windows: \Users\\AppData\Roaming\Adobe\Common
(My system for some reason had decided to point to folders inside the Lightroom preference structure.)
Then quit Premiere Pro CC.
Moved the .pek files to the trash from the improper locations. Restarted Premiere Pro CC, the audio waveforms redrew properly.
HTH