Summary
The Elder Guardian hitbox intersects with blocks when they spawn, causing them to be able to travel through solid or glass blocks, and the world border.

Expected:
Elder Guardions are pushed away from the blocks they are slightly intersecting on spawn, instead being allow to jump on them (like players who intersect a door).

Current behavior:
Elder Guardians appear to choose a random direction to jump (as if they are on land, or rather, not in water), and jump towards that direction. If they are inside a block or the world border, they pass through that block without issue.