Was playing around with the monorail system last night (which is wicked awesome, btw). Didn't have a monorail charger yet, so was using batteries to charge the monocart. Used to scrench to pick up the monocart and the 'cart popped off the monorail but the batteries vanished. Later on was playing around with cargo. Screnched a 'cart carrying cobble, 'cart popped off but the cobble and batteries vanished.

(latest Curse version, 26.3.159)

Yeah, it really is a minor thing. Not worth hunting down if it isn't immediately visible why.

This should fix it: 26.3.174

Yup, that fixed it. A minor bug, however, in its place.

When screnched and the cart ends up in your inventory it is temporarily invisible. Opening and closing your inventory makes it reappear or clicking on where it is supposed to be. As I said, it is a minor bug, visual only, so if it is to big a deal to fix leaving it shouldn't be a priority

I spawn the item in the world, so I am not sure if this is caused by another mod.