Creative Cloud: Unable to sync because file is locked

Hello there! I'm having trouble with the creative cloud file sync. It has worked effortlessly before (a few months ago), but now none of the folders will sync and this message pops up:

I've looked at the "Sharing and Permissions" option for all folders I try to sync, but nothing seems amiss.

I hope any of you can help me. I use this as back up, so I really hope to make it work again...