I have never changed the region code of my drive, and I am showing 4 changes left on mine. . When you bought the drive in question, was it new or used?
I'm also not thrilled to hear you are erroring out when you try to change the drive's code...
The reason I say it's not DVDFab is quite simple. Yours is the first complaint of this nature (that I have seen). If it was a regular occurrance, there would have been more postings about that problem.
It might be instructive if you were to change the firmware in your drive. The manufacturer's website should have an update to that coding. It might even reset your drive back to region 1, and not necessitate a further check in Device Mgr. to see if it can be changed.
It also might not do anything at all, but at least your firmware will be current.
Please try it and let us know.