When I add cover art to an MP4 I almost always use the search box in the upper right-hand corner of the cover art selection dialog. When the proper cover art comes up I select the one I want and click "Open". At this point the cover art either appears almost immediately on the tag panel OR the screen freezes, but the cover art still appears on the tag panel after about 10 seconds. Once frozen, the screen is totally locked up and the only way to get rid of it is to terminate it via Task Manager.
Note that failing is intermittent; once in a while it will work, but I haven't been able to sort out what the differences between working properly and not working are.
As an aside, I keep my old server online and because it doesn't meet the hardware requirement for Windows 11, it's still running Windows 10. So far, mp3tag has never misbehaved on that machine. Therefore, my gut feel is that the problem has something to do with Windows 11, and with the 22H2 version specifically.
OK, this really sounds like an issue related to your installation of Windows 11 22H2.
At the moment of selecting the artwork, nothing is written via Mp3tag yet and all the searching, selecting, and opening via the cover art selection dialog are standard features provided by Windows.
If you have any program installed that might also come with a shell extension (for thumbnail generation or other extensions of Windows Explorer's capabilities) and which you don't have installed on your other systems, it's worth trying to remove that one and testing without. No need to reply, if you haven't any of those or if it doesn't make a difference.
Florian - Thanks for the reply and the consideration. I was thinking from the git-go that it was Windows 11 v. 22H2 that's at fault, and not mp3tag, but I posted my inquiry here hoping that other people might have run into the same problem, and that we could pool our info and maybe find a solution. I can't think of anything that meets your criteria (extensions of Windows Explorer's capabilities) so I guess for now we just wait and see.
The issue with covers on MP4s appears to be resolved. I have been doing all my cover updates on an old Windows 10 machine for the past 10 days or so, but yesterday I absent-mindedly added a cover on a Windows 11 machine and to my surprise it worked. I've now tested adding covers on all 3 of my Windows 11 computers and they all work fine. I did nothing explicitly to correct the problem, so I checked the Windows Update history and didn't see any automatic updates that might account for it. I'm at a loss.
OK I'm officially bummed out now - I spoke too soon. After working a few times on Windows 11 machines, mp3tag now hangs up on them again. But - the very same operation (same process, same files) that failed twice on a Window 11 machine still works fine on the Windows 10 machine. And it's not a matter of network vs local, because the Windows 11 machine that failed and the Windows 10 machine that succeeded are both accessing the same data on the server. Anyway I'm just as tired of writing about this as you are of reading about it, so I'm going to give up. Again.
OK I think I've made some progress - I am about 95 percent confident that the screen-freeze issue occurs when the "Search Cover Art" box in the cover art selection pop-up window is engaged, and only in Window 11 (Windows 10 works fine). I find that if I bypass the "Search Cover Art" box and instead pick out the cover I want by scrolling down the list (which is a PITA since the list is long), it works fine. It's still a Windows 11 version 22H2 problem but I thought you should know.