I'm having the same issue, where RCS is stuck on "setting up"/verifying my number, despite RCS working for months. It would occasionally drop back to SMS in the past, and take a few hours to a day to re-verify. But this time it's been stuck verifying to the better part of a week.
I have Messages, Carrier Services, GSF, Play Services, and Play store installed, all with Network, Phone, and SMS privileges (if applicable).