This might be well known at the point but, just in case :
Intellect devourers tend to get stuck in place when a combat starts.
They keep using "Dash" but aren't moving at all.
- This seemingly always happens with Us if the player fails to "tame" him.
- This sometimes happens with the two Intellect devourers sitting near a body at the beach.
- This always happens with the one located a bit further in the crashed ship.