There are people more experienced than me on here but I used a separate psu for the power for the hopper and it didn’t work as it did not share the same ground , I ended cutting my laptop cable for the hopper / coin mech power and all worked ok .
I think when my hopper was paying all the coins out in one go the wire what went into either the I pac or the pac drive had come loose (can’t remember which ) so the hopper got the notification to start paying out but was not getting the notification to stop hence all the coins coming out
I had the same problem with all the £1 coins coming out in one go the other week and one of the wires (ground I think it was ) was not connected properly once connected it worked fine , I no you have probably checked them a million times already!