The AI is having some issues

[RavenFeather]

Hello, I've decided to go back to the game after not playing it for months and I've been noticing that the AI doesn't behave like it should. The enemies spot me regardless of how dark the room is or how far I am from them which was a great annoyence after playing through the main story again. This also happens when playing Custom Stories and Full Conversion Mods.

I've tried to fixing it and looking it up online but I wasn't able to find anything. I was wondering if someone knows a way to fix that little issue.
Apologies if this is a common problem, and thanks in advance!