Simple Red Stone brewing stand.

Expected Behavior: Pressing the button, empties the stand from the bottom hopper and then fills up the brewing stand with bottles from the left and right facing hoppers. Works in Vanilla single player 1.11.2 and all previous version.

Actual Behavior:  Pressing the button empties the brewing stand HOWEVER, the left and right hoppers remain locked and new bottles do not flow in. It behaves as if the hoppers are still powered / locked.

Confirmed on my locally running server and on smp.boamor.co.uk (8 versions behind)