Has happened in multiple situations if an AFK player dies near an item sorter and doesn't respawn for a few minutes. One or more of the comparators breaks. The comparator that breaks displays buggy behavior: not updating when items are placed in the hopper unless set to or taken out of subtract mode, at which point the comparator will update correctly, but will not update again if items are taken from the hopper. This causes items to flow through the filter until it's empty, or causes the filter to back up and stop sending items through entirely.