Well seems like i was able to replicate this issue 3 times in a row, but no luck this time, still i'll explain it again if my sentence didn't make sense.
In order for this to happen, you need to be
- Have a 5 minute duty cooldown
At a hospital, healing (your energy bar is actively getting filled)
And when these conditions are met, if you try to go on duty it will send you to the menu, instead of a message mentioning the cooldown. Not a serious thing, and you still can't go on duty but it's a weird thing.