AvatarNathan Richer

Hmm how are you foam rolling? I would recommend going across your quad versus rolling lengthwise, meaning you should find a tight spot on your quad, then rock your quad back and forth slowly on that spot (ie. the pressure wave). this is instead of rolling the quad up and down it lengthwise. you can also pause on a tight spot and contract/relax to see if you can get that area to soften up, and also tack and floss by stopping on a tight spot and then moving the lower leg.

You should try voodoo banding the leg. It really works wonders.
All the muscles on the opposite of the glute can inhibit it. it could be adductors, quads, psoas, TFL, illiacus. 
Here are some: