I have been working with a larger mod project for a few months now and I faced a simple annoying problem which seems to be unbeatable for me. I have a dungeon occupied by trolls but for some reason my trolls never tries to hurt player. They are hostile, they dance their fighting dance when they see the player and are showed as red spots in the compass but they never raise their arms to hit the player. You can stand at front of them but no they are not trying to hurt you. I have tried different AI setting and packages but nothing seems to work. With other enemies I haven't this kind of problem. So what's wrong with my trolls?

Not knowing anything beyond your statement it sounds like your dungeon needs a Nav Mesh... without one NPC's can basically do absolutely nothing within interiors -> IE: they spot you, go into combat stance but can not Path to you so they do nothing else. There are a few other reasons that this behavior can occur but missing/broken Nav Mesh is almost always the cause.

Thank you, I will try this out. I'm still trying to learn how to mod Skyrim properly - I used to mod Morrowind and then Oblivion but it seems there's a big difference between modding Skyrim and them. Many things (especially scripts) which I want to put in my mods I know immediately how to do them in Oblivion but with Skyrim I need hours to figure out how to get them working. This troll issue have been there for weeks but I have let it wait again and again when I have been working on other issues but now it bothers me too much.