With a mix of types like that, my guess is the thumbnail threads all got stuck/delayed on files for some reason. (E.g. a video file that made a codec spend a long time on it, or even hung. That would usually only affect one thread but a lot of similar files much block several.) That or something was blocking Opus from accessing the files the first time, perhaps.
For what it's worth, I rarely map drive letters here, and use UNC paths with thumbnails a lot, and have never run into the same issue.
There isn’t, but they shouldn’t be stalling either. It likely means something has installed a shell extension or codec that has a bug and needs updating or replacing.
If you make some process snapshots while that message is displayed, we may be able to use them to identify the problem component or at least the file triggering it (which may be enough to work out the component).
Here is some more detail on one of the thumbnailing problems I am having.
After reinstalling windows, a local directory that opus was thumbnailing correctly no longer thumbnails the videos in there but does do the images. Originally my main computer was not thumbnailing the videos in that folder, but opus using the same backup/restore file was thumbnailing the videos on the other computer (before I reinstalled windows).
Not sure if that is understandable or word salad.
Let me try explaining this way:
Computer A accesses network folder named media ->vidoes not thumbnailed, but images are
Computer B access local folder named media -> videos and image are thumbnailed
After clean install on Computer B
Computer B accesses local folder named media -> videos are not thumbnailed, but images are.
Could this be a codec problem? The videos play fine.
I just tested this folder with windows' file explorer and it isn't thumbnailing those videos either.
I have no idea why it worked locally before clean install but doesn't now...
(Due to copyrights, I can't send you the videos to test.)
That implies the required codecs aren't there (or something else is broken on the system). If the videos won't thumbnail in Explorer then they won't in Opus either, as we get video thumbnails via the shell.
So even though the video player can play the videos I will need to install the codecs so windows can thumbnail them. Does that sound right? I do remember the olden days of having to install codecs, but it's been ages since I remember needing to do that. I will see what I can find.