I submitted a bug report. I managed to find a case where this happens with vanilla long handed inserters as well, so maybe they'll have to listen now. Well, it's a pretty low priority bug, but one can always hope.

This is an issue that mostly occurs with modded inserters (such as Bob's), as diagonal inserters ar not available in the vanilla game. However as far as I understand the problem isn't caused by the mod itself. As seen in the attached picture, inserters that are diagonally in front of a cargon wagon ...

I don't know if this is a problem with the adjustable inserters mod, or with the core game mechanics, but it's obviously only reproducible with adjustable inserters so I thought I'd ask here first. Basically, if I'm trying to unload from a wagon using an inserter that is diagonally in front of the w...