A new update for Premiere came out today, and it's a small one but a much-needed one that was causing issues for lots of people. This update fixes the deleting cache problem that was introduced with the feature to audio delete the cache after an X number of days. The problem was that it was deleting cache all the time for some users. In some cases even deleting original media, YIKES!
“The update changes the behavior of the media cache deletion. With 11.1.1, only files that are within the Media Cache folder’s subdirectories will be deleted. Files that sit next to it will no longer be affected. However, we still strongly recommend keeping the Media Cache folder separate from your original media.”
It's a good thing they got to the bottom it fast but as the quote above says I would keep your media and your cache separate. Luckily for me this is the reason I never had an issue with this bug.