Hello,

Please forgive the very elaborate steps to reproduce this issue. I have not fully investigated all possible ways to produce this bug, so I will provide an example that works 100% of times for me:

-Set up an Assembling Machine 3 that outputs to a belt with an inserter.
-Set the recipe to ...

I have also encountered this problem once before. It was after a very long play session as well.
I am on Win8.1 x64