It may not be the same cause, but a similar symptom happened on mine. I found out in a roundabout way that my 64GB SanDisk microSD is shot. The card is stuck in readonly mode. It reads fine but cannot write, and the ROM just didn't complain about it and shows stuff from short term cache. Amazon reviews and forum posting showed that there are other owners of the 64GB SanDisk microSD with the same issues, and it was due to the controller going bad.
Plug your microSD to a computer. If you can create a folder on it, then your microSD is still good and the problem is elsewhere. Good luck!