Alright I spent some time trying to reproduce the bug, hoping to be able to avoid it for my next playthrough. Here is what I did
Start a new game with two mods, Cheat Commander to allow me to speed my way through to the shriekers in Act 1, and a very simplistic mod modifying difficulty a bit. The mod in question only has Stats modification for _hero and and HardcoreNPC, as well as some extraData Data Changes for some QOL improvements. Nothing really fancy. You can download the mod here : https://1drv.ms/u/s!Au29I7u16grFoIwUK6s18K_VfYD1uw
I start in the boat, I speak to the Cheat Commander, I give myself very high level (20), a few high end items, I save. I deactivate the Cheat Commander mod, I let the other mod in.
Arrived in Fort Joy, I speed my way through to the Shriekers at the end of Act, and they appear on the ground. They are still there, but on the ground, like they fell through. Interestingly enough, the one you encounter before near the old ruins is still happily standing on his cross.
Some screenshots to demonstrate that :
Near the old ruins : https://1drv.ms/u/s!Au29I7u16grFoIwV-VI4EWeXpRZKdQ
End of Act 1 : https://1drv.ms/u/s!Au29I7u16grFoIwWnDLEtl_ffH0Vmg
End Of Act 1 after save / reload : https://1drv.ms/u/s!Au29I7u16grFoIwXuxQOoXRT96Ym-Q
So, at that point, whenever you reload the game, the shriekers are gone, and you can't do anything to prevent them to do whatever they do.
Now, where it becomes interesting, is that I now deactivate ALL mods before loading Act 1 (so in the boat, I deactivate all mods, and load the game in the boat and then I leave the area). Act 1 loads first time WITHOUT any mod (as a reminder, the very little mod there was before was not changing much, still it was enough). I speed my way through to the same place (I'm still level 20, so it's quick) and this time, the shriekers are appearing correctly. Better still, I leave the game, load a buckload of mods, and ... the shriekers are still there appearing correctly.
Please note this happened following the latest patch. I always played the game with mods and never had any issue.
So the workaround for the moment for anyone playing the game is fairly simple :
Before changing Act, deactivate all your mods, load the new act, save, quit the game, and activate your mods back. It should work, it did at least for the first act.
I hope this helps Larian fixing this gamebreaking bug. Yes, it seems to be limited to modded games, but despite this game being great, It's still better with mods
Thanks for reading this
