I have had 2 instances of cargo randomly flying into the sky and getting stuck floating up in the air where they can't be recovered from both happened when a truck with a crane attachment was on truck nearby. First time was with the small cargo crane trying to load drilling parts onto a scout flatbed in Black River while playing co-op. Second time while retrieving vehicle spare parts I dropped in Smithville Dam using the heavy crane I just pulled up beside the truck with cargo and it dissapeared.
Have also had issues when lowering cargo onto a truck with a sideboard bed the cargo will pass through the truck but when raising the cargo up after it as passed through the truck it becomes solid and lifts the truck and damages it.
Also tried to swap trucks while cargo was suspended in the air with a crane to adjust position of the truck I was loading. I couldn't swap through the "change truck" option had to go to the map screen to swap trucks after which I got a message saying I needed to detach cargo from the crane to proceed. The message wouldn't go away after detaching the cargo. Completed the task I was doing with the message on the screen but when I got to where the cargo needed to be delivered there was no "cargo management" prompt. Had to load to a garage on a different map and return back to my truck to fix it.
And final major issue I have had is I had 1 drilling spare parts "packed" in sideboard bed and a 2nd drilling spare parts in the bed but "unpacked". If you have 1 cargo packed and want to pack a second one you must unpack the first then pack both but when I unpacked the cargo the 2nd drilling spare parts just vanished entirely. This incessant happened while playing co-op and the host of the session wasn't able to restart the mission so the mission now cannot be completed.
Not really a bug here but kind of a adjustment I think should be made that I'm sure others would agree with is that in the above bug I mentioned that cargo needs to be unpacked before packing another cargo but that doesn't add anything enjoyable to the game it's just annoying and frustrating at first when you don't know about it and can't figure out how to get the 2nd piece of cargo onto the truck. Would be much simpler if you could just have a pack cargo button and have it pack automatically if there is space but give a message saying "insufficient space" when there isn't enough room to add another cargo