Date and time formatting not respected

There are two settings for 24hours in the System Settings, one in Date&Time, and one in Control Center > Clock, far down at the bottom of the Control Center settings, Menü bar only: Click the Options for Clock.

Sorry, I cannot set the language to English right now - just to show where the second 24h Settings are.

Does not work on my 2017 imac running ventura. The option for a 24 hr. clock is grayed out - inactive. I tried accessing the clock via the 2 methods (they both bring you to the same page) you mentioned. This happened after I activated "voice announce for time", and then de-activating it. A bug, perhaps?

I see what you mean on your machine. it seems to be working properly here. however, it's only 12:38 here. I'll report back after it becomes 13:01.