I just updated to the beta. I'm on Google Fi, however it seems my SIM card is no longer being recognized and will not activate. Currently waiting on Fi support to see if it can be fixed at the moment.
I don't believe that Fi support won't be able to help you with this one. Try restarting your phone, if that doesn't work, you'll have to wait for an update. Otherwise revert back to 3.0.
Please send us an error report from the Samsung members app -> Beta Feedback -> Error Reports with a screenshot of settings -> about phone -> status information -> SIM Card Status along with logs.
