I've been making oven fries for many years. My method: wash potatoes (Russet), dry, cut, toss with olive oil and sometimes seasoning like paprika, no salt, bake in hot oven on low rack, turn with spatula 2/3 way through. Result: nicely browned, crispy fries. Inside is fully cooked yet firm.
I recently saw a recipe for oven fries with a spice blend I decided to try: paprika, pressed garlic, salt, pepper, rice flour, olive oil, all mixed together and tossed on potatoes. Otherwise, exact same method of prep and cooking. (The recipe said either rice flour or semolina or bread crumbs.) The result is they look beautiful on the outside and the flavor is great but they are not crispy and inside the potato is mushy. There was nothing else cooking in the oven that could've caused excessive moisture.
Rather than experimenting to try to figure out why they are so different, I thought I'd ask: What is it about this new blend of seasonings that is preventing the fries from getting crisp and making the inside mushy?