I was testing adding bundles from a cart to a build project, to see if they could be added to a project from inside a bin in a cart. They can not, just as any other binned item in a cart. However, after successfully adding them from the cart slot instead of the bin, when I attempted to remove the materials and return them to their original stack in the cart slot, instead of the warning that the stacks can't be combined there, I received an invalid inventory request error. I then tried to remove the items to an empty cart slot and they vanished with no error message. This is consistently repeatable.