So I'm not sure what makes this happen but when I uppercut sometime it doesn't show the animation, but the enemy still gets hit with the uppercut, also when you get hit with this "phantom uppercut" you can't cc break the knockup and you are just dragged all over the floor. I think it has something to do with weaving heavy attacks with uppercut, but yeah this needs a fix please and thank you.
No it does not affect snipe.
This is a glitch with Wrecking Blow and Heavy Attack only (as far as I can tell).
What OP did not mention is often one of the attacks, either heavy or WB do not do damage. You will see/hear the swing and hear the impact but the target will take little to no damage from one of the attacks. This happens almost as often as the bug itself, though it's not guaranteed. Sunshine and I were testing this.