If your handle is not unlocking when it should (or seems to unlock every now and again), but the solenoid operates correctly in test mode, remove and check the "arms" or "blades" of the handle optic. These are the parts of the optic that house the LED emitter and receiver.
Mine was doing this and the cause was one of the arms of the optic was broken and would cause the optic to appear as blocked/blinded (the optic is blocked when the handle is unlocked), and it seems the game will not activate the solenoid during normal play if it thinks the handle has already been unlocked.
I removed the broken plastic and reinserted the optic and all is well once more.