As you can see, current version, can’t write to a few particular m4b files. Files play fine, I have tried tagging them in the same network folder where I am successfully tagging many other files. I tried then moving it to a local disk and get the same error when it is there. No other processes are accessing it, I haven’t seen a tool to verify integrity of m4b files but if there is one I’ll try it. Please help if anyone can.
I've sent you a link via PM, with details on how to share that file for me to analyse.
I did not realize that foobar2000 worked on m4b files. I grabbed that and checked these files and they are damaged:
Error: Object "mdat" at 3734176 bytes is truncated.
Error: Media data is truncated, the file may not be playable completely.
This is resolved