When an automaton, say a Hunter chases the player and touches the ground in doing so, quite often it will get stuck.
In this case it will simply keep on deforming in the same spot.
Even going in Survival with fly mode right above the automata doesn't update their behaviour. It will stay put despite having a target closeby.
The automaton can still be destroyed and other behaviour seems to be normal, but when the automata can never chase the player efficiently they are fairly easy to take care of.

Though I can't be certain, my assumption is that the automata now test if the target is in sight accounting for obstacles in the way.
(if the player hides behind a wall the automaton can't see him/her)
If this is indeed the case it could be that upon touching the ground the automaton considers the ground to be an obstacle and is no longer capable of seeing any player?

I see now that in the animate spell a Target Location is meant to be updated, could it be that this is not happening for automata for some reason?

Found out they don't just get stuck in the ground, they can get stuck anywhere, mid-air too.
Occasionally the automata say ' has locked on to you' after which it moves another block in the player's direction only to lose track of the player again.
Something is causing it to lose track of its target almost instantly