Track 1 Dropped when converting Album Name to Folder Name

I'm in the process of converting multiple disc cds to new folder names so they are easier to find in Roon. This is the ACTION I'm using:

Format value " _DIRECTORY": :album:

This works BUT at times I see the word "moving" flash across the screen when the activity is being performed.

Today I was looking through my files (all FLAC) and I noticed TRACK 01 was missing in some of the renamed folders.

I am now missing some tracks. This is not the case every time but if I have the cd in my possession it can be re-ripped. However many of my files aren't in my possession. I wish I could provide more information or give a concrete example of how this happens (or find my lost files).

Has anyone else experienced this?

I have a hugh collection. Almost 800,000 files and I've backed up the NAS that contains the missing files so I can't recover them.

For any of the albums that you can confirm a track is missing, can you find that file in the original folder that it would have come from? It is unlikely the file is truly deleted if you did not execute that kind of command. It is more about finding the missing files. I would guess that one or more of the tags in those files were not matching the rest when you ran the Format action.

He renamed _DRECTORY, so there should not be the original directory there anymore.

I had this phenomenon too in the past with some albums, that track 1 was missing. But I never was able to see a relation between these cases and my workflow, so I have chosen to blame individual mistakes.

We’re you able to locate these files though?

No. I have no idea what happened and no indication that Mp3Tag has something to do with it.
It is not so that I missed hundreds of Track 1, I think not even more than 10 of thousands of albums. But it was always Track 1, that was missing.