I also got stuck on initializing, after some time it just stopped doing anything and reverted to the update button. I restarted after running disk utility and now I’m stuck on “waiting”/ queued instead of initializing. Seems to be really making my fans blast hard while doing nothing. Eventually times out to error: BLZBNTAGT0000138F. It was working fine 8 hours ago or so.
2019 27" iMac with Ventura 13.6. Comcast ISP (if that matters)
EDIT: Just read further down in the Mac threads and this solution worked for me: