That could be it. If your Civ5 or your Documents/My Games/ are in a non-standard location, the installation of Vox Populi or EUI may be going into a wrong place (= it can go as far as creating the the standard folder structure).
I suggest the following:
1) Install Infoaddict from Steam Workshop again
2) Run the VP autoinstaller again
3) Check your C:/Users/#user_name#/Documents/My Games/Sid Meier's Civ5/MODs/ folder (on my cell, I hope I remember the path correctly)
4) Can you see the Infoaddict there? If yes, then this is the correct mods folder where the game picks the mods from. If not, find the correct one - it will either be of drive D: or under a different username
5) Can you see the (1) Community Patch, (2), ... (6a) or (6b) folders of Vox Populi in the same folder? If no, then it means they went into a wrong = standard folder
6) Find the wrong = standard folder and move all the VP folders to the correct = non-standard folder from which the game picks mods
EDIT: I will leave this here, as I spent quite some time typing it on my cell and someoneight find it useful

But I have only now noticed that you could activate the 6 VP mod components (all 6, right)? Are you 100% sure that after you clicking NEXT after activating the mods and not going BACK to the main menu??? Many people make this mistake. When in-game open the menu and somewhere below, there should be map settings and also list of active mods - can you see the VP mods there?