Thanks, curious what their opinion on this one is.

That was fast, don't agree with it not being a bug tho.

When inserting stuff into a train with pre-determined slots the inserter can get stuck. This seems to happen because the inserter grabs more items then there are slots free. For example it moves 3 items at the same time, when the slot has 2 spots free the inserter gets stuck with the item in hand ...