OK, now I understand. I saw a lot of the spinning beach ball after the S/R appeared to have completed during testing, too. I thought that GS was addressing whatever was causing it.
At first I thought that AC was busy computing how to merge the new information it received, but Activity Monitor showed no activity. That made me suspect that there was some kind of 'handshaking' going on with AC waiting for something.
If this is what you see - network activity followed by CPU mostly idle during the beachball period - then definitely contact tech support. They'll probably need a 'support package' generated right after you regain control - as it will contain the log files that indicate what was going on...
Bummed to hear about your experiences.
Karl
One of the forum moderators
AC 27 USA and earlier • macOS Ventura 13.6.6, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB