Refreshing the window did give me my hooks back, but they would disappear again eventually. I'm not certain as to what the trigger was exactly, but it seemed to be something to do with intercepting the projectiles that would be the cause of me losing them. Not sure how exactly you have it on the back end, but it's possible it is subtracting an extra hook for being destroyed, but still only restoring the 1 when it would've returned? It felt more common when I intercepted very close to my ship, but that could also just be because I felt under more pressure and thus noticed it more readily.