PlayStation 4 Pro
Harvesters spawn minions when you move a certain distance from them. Also I believe only Harvester with minions can do this.
Find a Harvesters with minions defeat it and minions walk a distance away and minions will respawn.
That is a good thing to build skill points and increase regional levels. Sometimes, if you stay around destroyed machines to long, other machines start coming into the area also. Not sure what you are reporting is a bug or the way the game has been for a very long time.
they spawn in because there teammates didn’t report in, the robots were sent to investigate the incendent 
, also waiting for a robot ambulance possibly, just take them out also so another group will show up to investigate that incident
Can confirm, OP.
No doubt this is the behavior the game has exhibited for a very long time, but I’d definitely consider it to be a bit of a bug.
Destroy machines, wander away, wander back (having gone far enough, but not too far), and the escorts are present again… Happens when playing alone, happens when playing in co-op as well, doesn’t matter.
Another strange thing that can happen is that if you lure the escorts away (say, with a radio) and destroy them, then the Harvester wanders away—beyond the player’s render range, such that the Harvester renders out/de-spawns—there is the possibility that any wrecks of the Harvester’s escorts may also de-spawn, leaving the player unable to loot their wrecks.
These two issues can flow together. Lure the escorts away, destroy them, the Harvester wanders off, the wrecks disappear…you go after the Harvester, the escorts have shown back up…rinse, repeat.
As for farming experience this way, or loot, I regard it as something of an exploit. Killing what should effectively be the same machines over and over again, instead of having to move along and hunt elsewhere…
The escorts should effectively be separate from the Harvester, and just grouped together in terms of route, pathfinding, and combat. Additional escorts summoned by the Harvester, too, shouldn’t de-spawn if just the Harvester has wandered too far from the player, or the player has run too far from the Harvester.
No magic loot farm, no magic XP farm, and no stays of execution for the player—if you get chased away from the Harvester, you should still have to deal with whatever has chased you away, no matter how far you’ve gotten from the Harvester, so long as those other enemies are still in contact with you.
