Fleuressa

https://gyazo.com/55d5579f80b7e07a365b697427d40316 Occasionally this happens, and it just walks back and forth between the hopper and rockfall. Never seems to fix itself. Any ideas on why it's happening? All I have in my inventory is a rune pick and hammer, but it has a full inventory of pay dirt when it does it and it seems to have already sent a load through the hopper but goes back to mining before collecting it.