List of files disappears when I'm in positions 1-2-3 from the top

Thanks. I just unchecked it and noticed that the filter bar disappears. In all the years I've used Mp3tag I've never used the filter function.

It is probably the most powerful tool in the mp3tag toolbox!

Which Icon do you call "Note-Icon"?
Do you mean the icon to open the extended tag view?

Could you also make a copy of these new files and try the same thing on a different computer, just to see whether it works there?

Next to each title is a musical note, which is what I click on to select the title.

image

@poster has pointed out to me: it looks like you use a onedrive folder.
Could it be that the sychnronization process interferes with the editing?
What happens, if you treat the files in local-only and no cloud folders?

When I select the files, a popup in the lower right corner that says it is downloading the files. I'm assuming that means a local folder is being using for the editing itself.

If you can live with that assumption ...
IMHO this adds uncertainty to the root cause of your problem, until it is clear that the problem also appears in local folders.

Could you please check the working directory of Mp3Tag immediately after loading the files and after the problem occurs and compare whether it has changed.
You can find the working directory in your tag panel above the cover image area.

This is the icon of your windows standard-player for this filetype. You cannot expect that other users of Mp3Tag see the same icon because most people use other standard players und so they see another icon.

I can only describe what is on my screen. If I click once on the note the title is selected. If i double-click on the note or the title the MP3 player starts.

I don't doubt that. My post is only a hint that you should not call this icon "Note-Icon" because it's your player-icon. Others users which have other players in use see other icons and may not know to what you refer.
A click at any place in the file-list will select that file.

11-22-24. Following the first suggestion, unchecked the Filter option under View. All went well this morning.

This would mean that you have entered a space character or something else a some time during the editing.
If you clear the filter field but leave it displayed, you should see that the files reappear.
Also, als @Doug_Mackie pointed out, you can check the number of loaded files and the number of displayed files in the status bar: