I’ve got a setup with three trapped chests, each hooked to an RS-NOR latch which lead to an AND operation which opens a door when all three chests have been opened. Behind the door is a fourth trapped chest which resets all the RS-NOR latches when opened.
I have tested the system multiple times with myself opening the trapped chests, and everything is working as intended. However, after the golem takes an item out of the copper chest, the system only seems to register the copper golem opening one chest, and then fails to register any subsequent trapped chests when the golem opens them. If I go and open the other chests myself afterwards, everything works normally, with an RS-NOR latch engaging as soon as I open the corresponding trapped chest, and the latches resetting when I open the chest behind the door.
I did some more testing, and it looks like the issue is that the experience orbs are in fact getting trapped above the grindstone when it is attached to the ceiling. In the linked video, I was able to draw the orbs to me by jumping beside the grindstone, but if the grindstone was in a recessed hole in the roof, or surrounded by half slabs, this hasn't worked, and the grindstone would need to be mined to get the experience.
It looks like the real issue is the the orbs are spawning on the surface of the grindstone with the largest Y-coordinate, when ideally they should always spawn on the "top" of the grindstone (which is at the lowest Y-coordinate when it is attached to a ceiling). Is there an existing issue elsewhere for this?
Just wanted to confirm that I have also experienced this with disenchanting some fishing rods, two pieces of gold armor, and a pair of leather boots. I'll try to capture some video with F3 debug visible the next time I have something to disenchant.
I’m fairly certain that this isn’t a bug. As I understand it, the Copper Golem doesn’t retain knowledge of which items are in chests it has previously checked, and it checks nearby chests in a random order. Thus, if it has access to the target chest and an empty chest, it has a 50% chest of finding the empty chest first and putting its items in there. The way around this would be to either have no empty chests, or to prevent the golem from reaching the empty chest until after it had already checked every other chest.