I have a sorting system that works just fine in single player, and on other multiplayer servers (no plugins). I built the same system here, and it worked fine at first, then inexplicably started holding up items in two of the hoppers.
I'm not used to lock/unlock/chopper protection commands on chests and hoppers. Is there anything I can do to make this system function just as it would in regular vanilla? I would go ahead and remove all protections, if that's what it would take, and trust to the honor of the community not to grief or tamper. Are there known glitches with the protection system?