Wow ok, found two bugs for the price of one with this one.
The first bug I found was kinda unrelated, I don't think it could cause this problem. It just meant players
could enter a mission vehicle that they weren't supposed to be able to - the stolen vehicle in the 'Stolen vehicle (parked)' cop job event.
The second bug - which caused your issue - was to do with the very same cop job event - 'Stolen vehicle (parked)'. When that mission starts, it picks a random parked car in the city to be the stolen one. Guess what it doesn't check? It didn't exclude personal vehicles ;_; Your vehicle was marked as being used by someone as part of that mission. The state never gets cleared until the vehicle is destroyed or gets respawned..
To verify this, I destroyed all vehicles and called my PV so it was the only vehicle for the script to choose, and guess what...
Fixed next update! Thanks.
EDIT: Make it three bugs for the price of one... it was also able to select vehicles in completely different virtual worlds... At one point it selected me the vehicle that drives up and down the street on the login screen ._.