Migration Assistant : Authentication Failed : Unable to retrieve credentials for authorizing user.

I've been at this for hours.

I'm trying to use Migration Assistant to transfer some user profiles from my M1 MacBook Pro to my father's M1 iMac. Migration Assistant on my M1 MacBook Pro is where the issue is occurring.

I open Migration Assistant on my Macbook Pro, click "Continue", and I received the error mentioned in the subject before even deciding what type of migration it will be.

I'm running Big Sur 11.4 (the latest version)

I've already successfully migrated from my father's M1 MacBook Air to his iMac, it's just my M1 MacBook Pro that's having this issue.

I've tried restarting to reset the SMC (even though M1s technically don't have it). I've tried resetting NVRAM/PRAM. I've tried reinstalling macOS. I install Apple Configurator 2 on my father's iMac and used that to Revive the firmware on my MacBook Pro. I've tried changing my password and also turning off FileVault.

So far, only one thing has almost worked. I logged out of my user account, into another user account, then back into my user account while the other account was still logged in, opened Migration Assistant on my account, was told that I had to log out of the second account, switched users to the second account, logged out, opened up my own login again, and hit continue. That allowed me to go one step further.

At that point, I got a different error message saying my computer could not be used to migrate data, due to an issue unlocking the system. I can't quite remember if that's the exact error message, and I've been unable to get that far again.