There is a known bug that has been reported multiple times for both Detonating Arrow and Flurry which causes them to miss a lot. There is another bug with Flurry when you spec into the Multishot node that causes it to act like a machine gun, which sort of mitigates the misses for Flurry.
Here are a couple of them:
Flurry and Detonating Arrow…
Flurry hitbox bug