That's odd. Don't think i heard something like that before.
I'm not sure what could've caused it.

You did the usual troubleshooting, i assume? Especially the refreshing ini files part?

Well, that's embarassing. I totally missed that post!

Refreshing the .ini files did the trick I think, first mission after the restart I ran into a Sectoid Prime Negator in my very first pod. Of course, the rest of the pod was MECs and my final trooper picked a different way onto the roof and ran past a window with a civvy that rumbled my whole team, so it's micro-missile fiesta!

Thank you for the help and I apologize for not doing as much legwork on the troubleshooting as I should have - fairly new to modding the game and wasn't aware of that trick.

I would like to say that your mod is simply AMAZING and having it + Long War is easily the same quality as the Enemy Within expansion for EU. The sheer variety of enemies is incredible and the AI changes are scary as crap. I already almost lost a team to a Codex that decided it was in good enough cover and ignored its chance to scamper in favor of dropping a vortex on the guys who were supposed to overwatch ambush.

On further testing, this did not fix. After that one mission I went right back to getting regular Mutons and Sectoids, and no Spotters. It's also possible that I'm missing other variants, but since some of the variants show it's hard to tell whether they're not available or if they're just not showing up.

As before, there are plenty of ABA-only variants showing up, but just certain types missing.

Sounds like RNG to me. I didn't deactivate vanilla enemies, so you can still get them. Especially vanilla Mutons are plentiful because i have only few variants for them.

The Mutons I can see, but there are 5 variants of Sectoid and none are appearing.

It seems really unlikely that I would go the entire game facing nothing but base Sectoids and Mutons without seeing a single variant. I think the Sectoid Primes are getting handled differently because they DO show up, while any pod that has Sectoids or Mutons contains nothing but the base version. To compare with another class that's working okay, an Advent Pod will occasionally have a vanilla guy while the others will all be special. A Pod containing a Codex and 4 Sectoids should have at least one of them being a variant, but what I'm seeing is the Codex being a variant and all 4 Sectoids base. This has become more evident now that I have the Shadow Chamber - whenever I'm offered three missions I go through and check, and there are never any Sectoid variants, Muton variants, or spotters.

I think I'm just going to have to remove all my mods and then enable them one at a time until I find out what's causing the conflict. It has to be something really obscure, because ABA was the last enemy mod that I loaded and it was working initially, so it was some utility mod that started clashing.

What you are missing is how the game makes ALL alien followers in a pod the same. So yes, getting 4 Sectoids in one pod is perfectly normal. In fact, getting diffetent alien followers in a pod like with the Advents is impossible with the current spawn system. Sectoid variants can only appear in the leader spot of a pod for that reason. This is a functional difference between alien pods and Advent pods and a part of the vanilla game.
Sectoids and their primes are handled the same way, btw. If you get one, you can also get the others.

Now, it's absolutely possible that i need to raise a spawnweight here and there, but nothing you said so far indicates any sort of bug. Just some bad luck mixed with confirmation bias.

Hi. In campaign's first mission, where you investigate the secret site of Advent , the acid released one of the Chrisalyds, affects all units of a enemy POD ( muton , solider , and viper ), during his guard. It's random or it's normal? IA lack of precise at this point ?

That can happen from time to time if pods patrol very close to each other. I don't like it either, something i should finetune at some point.

yes, it was on patrol time. No problema, just curiosity and amazing to see it the first time that I played with the mod ;)