Trapper's Ambush still don't work with fragments and mods.
Bungie had long ago released a fix that in the end never worked and never addressed again.
The quickfall is not recognized as melee, doesn't work with melee fragments, doesn't work with the melee mods and if I am not mistaken also don't work with one-two punch.
So with the new patch about the fragment slot, I hoped that they would had fixed all those problems or at least noticed...and nope.
So please Bungie fix this, it would help a lot with the gameplay loop when using other exotics outside of omnioculus.