Yeah, that's it. Didn't think they'd instantly jump to it without actually putting it in my inventory. There was also no sound so I thought it was a bug.

Save was started somewhere around 0.13.12. No mods (working on lazy bastard). I'm setting up an oil train and I reserve slots in the car for a few stacks of full and empty drums. I made a new train with one car, got in the engine and auto-rode it to the oil drop off which started filling the car ...