Comment to Cannot Upgrade to RC1- nothing happens....
using 8.3, always have. so what now?
If you have PHP 8.1 or newer then check if UNA cron jobs are setup properly, to check it, go to Studio > Dashboard > Host Tools > Server Audit > Last cron jobs execution, it should be within a minute from now.
And yes, It was....
You clearly state that cron is running on PHP 7.4. Change the cron version to PHP 8.1 or newer and everything will be updated.