this is pretty self explanatory zombie pigman can can detect players through blocks as such it is causing them to stay agro indefinitely wether I enter the overworld the end as soon as I reenter the chunk with the pigman their aggro is retained meaning even if I surround myself in blocks they still try to harm me the only sure fire way I have found around this is to kill all aggro pigman within the hostile mob spawn area but if you are not fast enough pigs when spawn and spawn keeping the aggro no matter what