Iron Golems spawning with part of their hitbox inside a nether portal block won't go through, even if they walk through a different portal. 

UPDATE: Turns out the Iron Golems aren't going through because they interact with a portal block that isn't linked to an Overworld portal, but still go on cooldown. Removing all portal blocks that doesn't link and being left with only blocks that do fixes the issue.

Unsure if the cooldown is bugged here or working as intended. They have interacted with linked blocks for much longer than the 15 seconds they should be put on cooldown for, but maybe they need to not interact with any portal block linked or otherwise for the entire 15 seconds?