Double check the unlocking list in the Go app and make sure it's turned off. This just happened to me recently after a firmware update. I was already unlocked for a specific NFZ so whenever I fly there, I have to go turn it on. But per DJI (and they were correct), if you are flying in a non-NFZ you need to turn off the unlocking list or it will think you are in a NFZ even if you're not..
I have never used it. I will check this the next time this happens.
Interestingly - I went back to this location tonight, 2 am, took off and flew no problem, same place, nothing changed,
DJI has a consistency problem here of some nature.
I wonder if there is a server being contacted in real time and it's timing out so defaulting to last NFZ in effect, or something similar.