I threw a loyalty III trident in the Nether and it landed in lava. I saw it flying back to me with the fire sprite over it. It flew past me a bit before flying around me since I was moving. Then as it swings right in front of me it disappears about 10 blocks away. I tried relogging or picking at the slot it should have landed in my inventory but it didn't return. Upon entering the overworld  it returned to my inventory. There was no way for it to have gone through a portal.