As I clicked the button, the cost to repair my gear went down to 0, greyed out the button, and nearly instantly, the window closed from moving out of range of the NPC. Not sure if it took the funds to repair or not, but my armor is displaying full durability, but none of the pieces are giving me stats. Unequiping and reequiping doesn't fix the issue. Equipping other items into those slots give stat bonuses as they should. Equipment remains unable to be repaired.
Dying did not cause the repaired armor to lose durability.
Leaving game and joining a new one caused my armor to show 0 durability and be able to be repaired again.