1. Were you shooting double action or single?
2. A pic of the innards would help immensely. These are relatively uncommon revolvers despite the fact they've received several glowing reviews on Youtube. Few of us are familiar with them; do they work like S&Ws, Colts, or something else?
Without knowing a thing, I'd hazard a guess that the rebound gizmo, however it works, is hanging up; or that the double-action sear bar (assuming the gun has one of those) isn't moving freely, or that the trigger is catching on it somehow. The fact that it only happens on one charge hole indicates involvement of the hand/pawl/cylinder-rotator-dingus.