ASUS motherboard UEFI boot issues

Is it normal for an Asus Prime board to totally choke out when I try booting a Windows 11 installation DVD via legacy CSM? Like, the installer actually starts up, but then after just a few seconds, the whole PC just freezes solid. Mouse, keyboard... nothing responds. Just dead.
The guys at the repair shop are telling me my only option is to do a UEFI install using a USB drive instead.

It’s kind of weird, though. Why would an Asus board act up like this if it literally has the legacy option right there in the BIOS?

Here are the exact specs
asus prime
B560M

Honestly, this is the first time I've run into an issue where legacy boot just won't work. I don't think I've ever handled a board quite like this one before.

I’m starting to wonder if there's some weird hardware flaw here... I mean, would ASUS really bake a broken option right into the BIOS? It seems unlikely, but who knows?

The USB installation itself boots up just fine, though.

It is a known phenomenon that sometimes, only one specific build of Windows 10 will install without throwing a tantrum.