Not sure how often this would ever come up, but Elder Guardians can't jump past fences on dry land, even though they jump about twice as high as they would need to in order to clear one.
MC-128037
Elder Guardians can't jump a fence.
Resolved
Invalid
1
The elder guardian is only able to jump one block high, which is not enough to jump over the fence. You can check that by enabling F3+B to view its hitbox.