I was trying to get back to that point rq so I could show you a screenshot but then I got this again
so in this specific case i have an inserter going to a box and then another inserter taking from the box into an underground tunnel, however the second inserter isn't taking anything for some reason, it just empties the box.
P.S I have discovered that the crafting materials needed for something randomly changes, sometimes crafting a furnace costs 2 stone sometimes 10 and sometimes 5