In the field you will have sat time. Does your local wifi have internet?
To induce time sync failure you remove internet and clear enough sat view.
I am in an old pole barn with steel siding so even a good antenna has a hard time getting time sync. This could also be true of say an emergency response or operations trailer with metal sides/roof.
Like I said, it could just be me and I have found an edge case. Just trying to figure that out.