I upgraded to a M1 based Mac Mini for my Roon core (I use it for other things too). I opted to encrypt the disk with FileVault. I noticed then that if my mac restarted, Roon would not be available.
I confirmed automatic restart was on. The mac was restarting but stopping at the login screen and so Roon would not start. I went to set Automatic Login but it was greyed out. It turns out you cannot have Automatic Login with FileVault on, i guess that makes sense as it would defeat the purpose of the disk encryption!
So I turned off the disk encryption (if someone breaks into my house and steals my Roon core, i have bigger problems!).
Thought I would drop this here as a tip for others using a Mac Mini core.