Some DVDs will not play in MPV, but they do in VLC

I have a number of Region 1 DVDs (certain discs of certain seasons of Home Improvement) which MPV cannot play, but VLC can. My drive is set to its default of Region 2, but while I wonder if this might be the cause of the issue, between the fact that some discs from the same sets work just fine — and all of them work in VLC — it leaves me apprehensive to waste one of my region changes to test such a hunch.

When I export DVDCSS_VERBOSE=2, I see the following among the output:
libdvdcss debug: ioctl ReadTitleKey failed (region mismatch?)

And I also see that LIBDVDCSS is failing to crack the key to one of the titles on these problematic discs (regardless if I set DVDCSS_METHOD to disc, title, or key), but I am not sure how VLC is managing to overcome the limitation? I even tried emptying the .dvdcss directory, loading the disc in VLC first (which I can see recreate a directory for the disc and its respective keys), then try again with MPV, but still to no avail.

I am running a live image of Debian 10, with fresh installs via apt-get of LIBDVDCSS, MPV, and VLC. I have also tried version 0.29.1 of MPV, so as to test using dvdread://, but it too fusses (floods the terminal) about missing headers, et cetera.

I have two optical drives, so permanently changing the region of one of them to Region 1 is an option. However, again, all discs play in VLC, as-is! So if there is something that can be done to get MPV to access the drive in the same way as VLC, obviously that would be preferable. If anyone has any ideas of what else I could try...

Start by reproducing the failure with the reported Region 1 DVDs and compare MPV's libdvdcss output, including the ioctl ReadTitleKey error, with VLC's behavior. Investigate the dvdread:// entry point and the DVDCSS_METHOD, DVDCSS_VERBOSE, and .dvdcss cases mentioned in the report; done means the affected discs play in MPV without requiring a region change.