I too have some in my Data file that don't show up - just noticed when trying to overcome Sceam -I mean Steam- issues - was gunna ask the same thing...

I know a way to fix it.
There is two skyrim prefs. One in docs one in steam folder. Go to the document one and put in this below [Launcher] bEnableFileSelection=1. That worked for me. Hope it helps!

For me the data file thing was greyed out. That fixed the thing
Yay I can mod succesfully!

When you open the launcher.

@I'mAfraidOfBunnies - forgive the extreme noobiness of this but - not sure where/what I put in below??

Go to documents. Go to my games. Go to skyrim. Click on skyrimprefs in that folder. BELOW [Launcher] type: bEnableFileSelection=1. Try it out

Hmm yep I seem to already have that in there :/

Some mods show up, some don't, in the launcher... grumblegrumble...
Thank you though ImAfraidOfBunnies :)

Always welcome.

i get failed to load from steam and mods that dont go in the game. what is this about pref doc? im new to this so please be patient if i dont understand right away as i am also new to steam :) i get loading errors from alot of mods. and it also say failed to find on steam or something like that
othherwise i can only say the mods i have workedd fine untill i decided to buy the 3 dlcs aswell. then everything went balloony on me. i then read that it is not all mods that work in dlcs. so i painfully removed everything from steam i could. but i also use some from nexus. so they stayed. falskaar amongst them. so now i can start up the game and play it, but it misses alot of mods because i maybe removed them and put it back so it goes bad ingame.or in loading it. so i am very interested in this if it could help me too. i use win 8.1 64bit. skyrim go in 32bit i think.

hmm dunno Well google has it all lol