I missed the belt loop too with the first Fenix I ever owned. All I saw was the plastic attachment ring at the top. I felt like such a fool when I discovered the double layer of material at the back which forms the belt loop.
If you can't see it, just gently bend the holster back, holding the top and bottom, and it will open up. All the Fenix holsters, except the T1 and TK10 have this. It keeps the whole profile nice and flat if you're not going for the 'outdoors' look.