When you drop a block of gold in front of a piglin it detectes that is a trade object and goes to grab it. Seconds later when the trade should be completed the piglin don't throw anything and also don't return you the golden block he grabbed. You better not throw a piglin a block of gold if you were expecting an amazing trade for nine golden ingots... It would be cool if it was changed and make them to trade an amazing amount of resources or simply remove the ability to grab gold blocks and dissapoint all of us hahahahahahahaha