I seem to be getting this same issue, but reloading the plugin didn't fix it visually (I haven't reloaded the game yet and will let you know once I have, but I would assume as this is specifically a visual glitch as everything is still there that a fresh load would make them all appear back. You can see from the screenshot there is an invisible door in front of me and there is actually several invisible chests and sleeping bags inside the cart as well.
It's my server so I'm happy to provide anything additional I can to support you in figuring out the cause, if you need any logs, etc.
