“Lock preferences” dialog after stopping playback?

I’ve been trucking along nicely for months now with no changes to either my network shares nor my coreelec setup, but I’m suddenly getting a prompt to “lock preferences” every time I stop playback of a file. It DOESNT do it if the file ends naturally or ends and the next file plays automatically, only if I manually stop playback.

It asks for a username and password (presumably for the network share), displays the network path to the specific file I was watching, and can just be cancelled out of to carry on doing whatever I want to do, but it popping up every time I stop watching something is kind of annoying.

I did enter the username and password for the share the first time it came up just in case, but it’s reoccurring anyway (and seems to be doing it file-by-file anyway given it always references the specific file when I stop, so having to do that even once for every file on my NAS would be an absolute nightmare even if it had worked.)

Does anyone have any idea what could be causing this behaviour? It’s literally only when I stop playback, everything plays just fine. My folders are shared from a NAS via smb and there’s been no change to this since it was set up, I’ve double checked just to make sure there haven’t been any updates in the background and there’s nothing on that side of things.