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

[ESSEMDEE]

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...

[ESSEMDEE]

It occurred to me that a difference between my tests with MPV and VLC the other day was my use of the discs' menus for the selection of episodes in VLC. (The only reason that I even installed VLC was for DVD menu support, so as to aid in figuring out what title is what episode.)

Wondering if that difference might have something to do with why VLC can play titles for which a CSS key fails to be cracked, I first tried directly starting a title via VLC with "no disc menus" checked, and the result was the same corrupt (encrypted) mess that I see with MPV.

I then tried with old MPV 0.6.2, and though I do not know how to directly launch into a disc's menus in MPV, by jumping towards the end of the corrupt video and letting it finish playing, I was "returned" to the menus and able to manually select the same episode that way, which subsequently played perfectly!

So this phenomenon is not some voodoo of VLC, but of LIBDVDNAV. Though, I still cannot understand why or figure out how I might be able to apply such a trick to directly start a title without the menus and get anything other than the unwatchable, corrupt mess.

Would uploading the problematic IFOs or anything be of help? It is as though the menus cause the disc contents to somehow be accessed differently than they are when specifying a title number...

[Dudemanguy]

Would it be possible to get a sample file of this somehow?