Custom Player Heads do not have a collision hitbox

[calebeden]

Vanilla mob heads have a collision hitbox, meaning that the player can stand on and run into them. The custom player heads do not, since they can only be equipped on entities.

[calebeden]

This is a limitation due to the implementation as armor rather than blocks. One workaround to this is to place one of the vanilla mob heads and use FoxyNoTail's Armor Stands add-on to overlay the custom player head directly over the mob head block.