iMessage on MacBook keeps signing me out

Hi,

So I have a 2016 MacBook Pro and I just updated it to Big Sur. I tried logging in to my iMessage and it logged me in but then suddenly logged me out, this has happened almost 10 times now. I also can't log in to my FaceTime on the mac. I can log in to my AppleID and iCloud on this mac, my iPhone, and iPad. But for some reason, iMessage and FaceTime will not work.

Also, I can't access preferences for iMessage or FaceTime either.

I have tried all the suggestions in Apple support and online. I'm not sure what else I could do?

Thanks!

- S