Seems to be something to do with Compositions potentially? Kept running into issues with all vehicle doors being obstructed (although they could be opened) and preventing access/exiting when near stuff like supply containers as well

I have observed the same issues. When they go beyond a certain distance from the player (unknown how far, maybe render distance? Or some sort of simulation distance?) they break. Sometimes it's temporary and a player coming close enough to them will fix it, sometimes they completely break and end up running on foot halfway across the island, only to bug out at the point they were delivering supplies to. It makes it very difficult to keep bases supplied in HQC now, especially with the FIA blowing up/deleting supplies.