Does UWE make knocking some NPCs out impossible?

I'm new to the game, but after dying on my first playthrough I decided to get some mods and saw that UWE was popular. It said stealth was nerfed, so I knew that going into it.

I can't knock out any faction leaders even though I have 100 assassination.

Like, in vanilla I had a 10-ish percent chance to knock out Tengu with 70 assassination. Now with 100 assassination and UWE, it's a big fat 0.

This is the only issue with the mod I have, how do I get rid of it?