I am in the exact same boat as you on the eternal reauthorise loop with no luck. It “authorises” in LM then as soon as I open BFD3 it has the “no authorisation found” message you have. What is weird is that the first time I opened BFD3 in stand alone it worked? I closed it and opened reaper and it haven’t worked again. Same just got an M1 and running Monterrey