While inside a vehicle accessing your inventory i have noticed a few things:

1. You cannot move items between combat fatigues, vest or backpack.
2. You cannot move items into or away from equipment belt for example NVG's.
3. If you attempt to move items around your inventory, you will also then no longer be able to move items from the vehicle into your inventory unless you reboot the inventory.
4. Unable to turn on NVG's while in a occupied vehicle. (Example, enter huron with AI inside and try to turn on NVG's)

These issues have existed since accessing the vehicle inventory's from inside was implemented.

I will briefly demonstrate the issues on a video, you can also try this out for yourself. https://www.youtube.com/watch?v=gWglRB4Sn8E
I run into this problem daily which forces me to exit the vehicle and then access my inventory.