If it stays frozen for more than 30 seconds, it's probably an interaction with something else on the system which has also changed, since we don't have any similar reports and 12.23 doesn't have any changes likely to cause this kind of problem.
But whether I'm right or not, if you make some snapshots of the process while it's in the frozen state and send them to us, we should be able to look at those and get a better idea of where the problem is: