Hey @dsminor thanks for the reply! Much appreciated. I've been hacking away at this since your post & still haven't found a solution (but I did remove the 'trigger once' you mentioned!).
Collisions are indeed activated. What's more curious is that every few runs, the 4th enemy actually moves! He walks to the first point and stops there! It happens seemingly at random, I didn't change anything.
A couple of interesting points:
1) if I disable the 'for each enemies' at the start of the patrolling behaviour, they all move! (The problem here being that they all copy the first instance's movement). SO I've ruled out something being wrong with instances themselves.
2) if I change 'For each enemy' to "for each enemy, pick by IID ascending" then the last 3 work, and the 1st stops working! It's bizarre.
Again, any suggestions, help or thoughts on this would be much appreciated. I see no reason why the 4th shouldn't work. I've checked to see if there is interdependence or if something is interfering and so far I've come up with nada.