Hi there
The ERM GUI shows me that I've got 31055/3155 Attack Points for Biters on Nauvis, yet there's no one attacking. I've noticed that only recently. A few days/weeks ago, there always spawned an attack group when the threshold is reached (here, 3155).
I've got no idea why they no longer do... I'm using many mods and planets, there might have been an update that broke something, but it was running fine for dozens of hours so far. Playtime 8 days, not progressed too far (was on Lignumius, Nauvis, Muluna, Vulcanus). I think I was designing a space platform and didn't look at Nauvis for a long time, and my production there tanked for a few hours because I wasn't paying attention, so little to no new pollution, but that's been up and running a long time again. These are the only clues I could imagine so far that might have something to do with it...

Do you have any idea where to look so that they attack again if the threshold's reached?

Thank you!

idk. please send me your map. I'll take a look the internal data.

For future reference: Any enemy force from 3rd party mod that eliminated an ERM registered force on a planet will prevent the ERM registered force's custom attack group from spawning.

Hi! Thanks a lot for looking into this! In my case, it was the https://mods.factorio.com/mod/ZombieHordeFaction mod, they killed off the biters and so there were none left to start attacks via the ERM mechanics.

I thought Zombies were "friends" to Biters, there's an option that puts them into the "enemy" force instead of their own "zombie" force. However, I discovered that setting too late, so I turned it on while already many hours into my game. Zombies placed until then kept their "zombie" force, and thus, killed off Biters ("enemy" force).

As heyqule told me, when new chunks are discovered, Biters turned up there eventually again. New Zombies discovered in the new chunks are indeed of the "enemy" force and hang out with their Zombie friends and have some tea, until my artillery shells rain down on them, then they join in an attack.

Edit: Told the Zombies mod, but I don't think it's really a "bug" over there: https://mods.factorio.com/mod/ZombieHordeFaction/discussion/6922db6532b4745b33862587