A Milhouse build release notes say "DVD ISO/disk playback remains temporarily disabled" so it doesn't play DVDs at all.
I tried the generic 7.0.1 x86_64 build on my PC. Same problem there, so it is not specific for Rpi.
A sample of one of problematic NTSC menus - Dropbox - Link not found
I tested multiple DVDs, the problem occurs with all NTSC DVDs which have static menu. There are no such issues with animated menus. Here's a video I shot with one of those DVDs:
LibreELEC DVD menu problem - YouTube
Also, notice how the menu goes all black except for some buttons after the screen switch to 50Hz.
