Negative, at least in my case. While it is true that, at least twice I used a UAV from inside the vehicle, at least once we took a car just after spawning (with a pilot, no UAV operator) and the error still happened. I am not sure if I had used a UAV terminal before in that same mission from inside a vehicle, so maybe the problem just seemed fixed after respawning and manifested itself again as soon as I got into a new vehicle. But I have no idea how this error works, so I cannot say for sure.
Anyway, I am not currently able to run the game and test things because I have no access to my computer, but as soon as I can, I will try to test this out with some friends and see what I can find out.
I hope this is just the problem you are aware of and that you can fix it soon.

Negative, this bug is new. I have observed similar things in arma 2 and older versions of arma 3 too, but this time it is not random desync but a consistant bug. I cannot tell if it happens 100% of the times, but at least 90% of the times I got into a vehicle it happened to me, and also, it seems to only happen to the host.

I am now trying out running a dedicated server on my PC to solve this problem until BI fixes it. Also, CzechTroller, did this ever happen to you while you weren't hosting? did it happen to other players when THEY where hosting?

Having the same problem, at least I think. What happens for me, is that when I get inside a vehicle and leave, the other players still see me inside the vehicle, even if I'm outside, so I'm basically invisible + invincible. I can kill them, as you experienced too, and they can shoot through me. They can, however, kill the ghost-entity that is sitting inside the vehicle (only they can see it, not the affected player himself). If the affected player blows up the vehicle by himself, he won't take damage (probably the damage is calculated locally, and sent to the server like "I shot player XXX", which would explain why they can kill the ghost entity sitting inside the car, even though it doesn't really exist). It also appears this only happens to the host, and was 100% reproducable for me. Every time I got into a vehicle and got out it happened, but never to anybody else. This also often happened together with the bug where I couldn't leave the vehicle, and whenever I selected "Get out" i was instantly teleported back in, as long as there was a driver, though this bug didn't happen every time, so they might be completely unrelated bugs. Anyway, as it is now, the game is basically unplayable.

I think this problem has been kind of forgotten, but it is still there. And I still cannot use mine fields in my custom missions because of it.

I am creating a mission right now that relies heavily on the mine detector to work, so right now it is almost impossible in elite mode. Mine detectors should definitely work in elite mode, beeping or something and maybe even beeping more often the closer you get.
I hope this gets fized fast so that I can play mi mission without having to find the mines by looking at the grass for an hour before every step I make.
BI, you guys are awesome, but you still have a lot of work to do.