i have the same issue , i have manual installed FNIS in MO ,the filles are in steam/steamapp/etc etc .....when i try to launch it ,it dt work ,just gimme a black window who will be there for 1sc before she shutherlf down ;but when i launch it manually (FNIS) it doeas work normaly,i have no AV software or else ,so i dont really know what i should do. i really whant FNIS on my skyrim ,i have played skyrim and skyrim special edition ,i've modded my skyrim special edtion but it wasnt the official thing,now i have buy my self skrim SE and wanted to get a clean stable mod thing and with a lot of mods but here i am waithing to get it right ! i hope people can help me and if not snif snif,thanks for reading this,hope you all the best (sorry for nazy grammar ,im not english)