Last month I made an IPA with some experimental grapefruit hops with 18% AA but the final product turned out with very low bitterness and low hopppy flavor.
The first thing in my head was that it could be because of the weak boil I had the day I brew it due to technical difficulties (208 F was my average boil temp.). The other thing a suspect could have messed with my bitterness is a larger than required pre-boil wort volume.
My hop schedule was: 1 oz @60 min 0.5 oz @30 min 0.5 oz @10 min 0.5 oz @5 min 0.5 oz @flame out 0.65 oz Dry Hop