A Microsoft file hosting and synchronization service.
This just started happening to me as well, and I tried renaming - no luck. I also created a brand new folder, and shared it between our accounts, and it started out as a link - so if this has to do with migrating, what is migrating. Given how much money all of us are paying for this service that is no longer working, I'm starting to think a class action lawsuit may be required. This is a breach of contract on their terms of service, and the don't seem too motivated to address the issue.
Does anyone from Microsoft have any actual plan to address this issue?