It’s been a long wait but we might have something here: Framework Laptop 13 Ryzen 7040 BIOS 3.16 Release BETA - I’m specifically looking at the issue here: Cannot boot from partially locked self-encrypting drives · Issue #42 · FrameworkComputer/SoftwareFirmwareIssueTracker · GitHub
It isn’t the bug they have open that references this thread, but it does appear to be related. It’s worth testing, at any rate, as it involves how the BIOS interacts with drives using OPAL.
I’ll install the BIOS update soon, and I’ll try to test the encryption when I can - although that’s a more time-consuming task because I have to wipe the drive of course.