I've heard of stuff like this sometimes happening (I think mainly with storage containers), but I can't currently get this to happen on my end with the buggy. Does it happen consistently for you?
Steps I took:
- Load game with a buggie
- Open buggie inventory
- Transfer a few items over, back and forth. Sometimes 1 at a time, sometimes via shift-click (move entire stack)
- Close popup
- Save + Quit
- Load game, same amount of items were still in the buggie that'd be expected.
Would love to get this fixed though if it's happening for you. Any other ideas on what steps / actions you might be taking that I'm not thinking of?