I had 2 mech clusters on my main map and some enemies incoming on a map, generated when encountering prisitne ruins. I took some stuff from ruins and decided to run, when another wave of enemies showed up. Once my pawns left the ruins, mechs on the main map have awoken but became completely harmless, they ignored me even after getting attacked. More than that, a message appeared in the top left corner: "Mechanoids have decided to leave".