Luks won't open on boot, will decrypt off live filesystem

My luks partition has never been a problem, but suddenly it won’t decrypt on boot. Off a live fs, I can luksOpen it no problem. I have tried setting a bone-simple passphrase from live fs, tried changing keyboards, etc, and the result is the same: no problem decrypting from live fs, but no luck on boot.

I have a much older nixos luks partition on a different SSD, with the same passphrase. Again, it decrypts from live but not on boot.

I would appreciate any ideas of how to proceed. Thank you!