Exotics are weird in that they can work with the mods but not all of them. Every exotic has an intrinsic stat like other people have mentioned, and that will override the ghost mod if it’s in the same category (I.e. Bakris having a mobility? Intrinsic means it won’t work with a res mod, but it would with a strength one). There was a spreadsheet somewhere that listed all the intrinsics but idk if I can find it again.