My wife's 2011 GMC Yukon Denali's NAV had problems after we experienced a meltdown. 100,000 miles. Running 80. Doors started locking/unlocking/locking. Everything on the dashboard was flashing. Headlights flashing. Horn honking. GMC is losing speed rapidly, but still running. Finally get it pulled off the freeway, swallowed hard, and shut everything down. Waited about 10 minutes trying to figure out in my mind what went wrong. I started it up. Everything worked fine. Except there was no time on the NAV. Blank. About a year later a time appeared on the screen. But it was random, and was not keeping time. Just switching it as it damn well pleased. About a year after that the time came on when we started and it was right. But it never changed. But we noticed everytime that we started it the time would be right, just never change. Hell, we are making progress. Then about a year later it came on, stayed on, and is keeping time.
The only remainging problems occur when the low fuel light comes on so does the NAV. Not what is supposed to happen, but it is a nice thought by the NAV. Then on rare occasion the car will just lock itself. We learned how to live with that, which is take the keys whenever we step out.
I went to my GMC dealer and told them to check every ground wire they could find. I figure about 30-40 of them. Unplug, inspect pins, plug back in. Loosen the bolts/screws, retighten. There is a major ground on top of the transmission, which means the transmission must be removed. I passed on that one.
The moral of the story is to check every ground wire you can find, then be patient. Ours was a little petulant at first but finally came around. Up to 175,000 miles now, with the last 15,000 being worry free, absent the two remaining things. Still low fuel equals turn NAV on, but no big deal. Still on occasion will arbitrarily lock the doors. We solved that one by taking keys.
By the way, who uses Navigation on a car anyway? That is what mobile phones and Apple CarPlay are for.
So it happens. In my case it substantially resolved itself.