The only thing I can suggest is to do a System Restore back to a restore date before this started happening. If that will not work, the SFC SCANNOW run from an elevated command prompt would be the only alternative. The following comment is IMHO only: this is another example of why I simply do not trust Windows utilities in general. You can spend days (literally!) trying to troubleshoot this glitch and never find it.
I suggest a 3rd party utility called "Macrium Reflect", free edition. I have been using it for years, have done numerous backups and restores, and it has never failed me yet. It has a top reputation here on Bleeping Computer and many will recommend it. In addition, you have realtime search capability for each image, so it is possible to access data directly from an image made months ago. Two or three clicks and it is mounted and running.