When the assembling machine only haves one category to craft, it seems like it takes the last category you clicked on, and places it like if the assembly machine could craft some item from that category, but if you click on it, it wont do anything.
Assembling machine-item categories
Re: Assembling machine-item categories
Thank you for the report, this will be fixed in 0.7.
In the case, that previously selected item group has no recipes for this machine, first non-empty item group is automatically selected.
In the case, that previously selected item group has no recipes for this machine, first non-empty item group is automatically selected.