ZOS, with the Murkmire patch, dizzy swing is now completely unreliable and broken. It was always a challenge to reliably it this ability, especially in lag and against mobile opponents that circle around you. Right now though, it is completely broken. And I think this has to do with what you changed in the aiming system, to make templar jabs hit more reliably.
You can test this on any mob, player or dummy. Try 3 different things:
1. Stand still in front of the dummy, and cast dizzy swing, while aiming at the dummy. It will will not cancel.
2. Use dizzy swing while moving backwards and forwards, aiming at the dummy. It will not cancel.
3. Use dizzy swing while circling around the dummy, while trying to aim at the dummy. You will notice that it will sometimes cancel.
When I repeatedly tested scenario 3, I found out that the moment you take your reticule off the target just one tiny bit, the animation will cancel. This practically makes dizzy swing useless for pvp where the target will be moving around, and through you, and where you will be snared very often. This was always a problem, but with this change to the aiming system or w/e it was that you did, it just doesn't work at all anymore.
What I often used to do to force a hit on dizzy swing was activate dizzy swing, move through/past the opponent, turn around and hit your opponent while moving towards him. This now isn't possible anymore because by moving through/past the opponent your reticule will be off the target for a fraction of a sec. It is unrealistic to be able to keep the reticule on target 100% of the time in a pvp battle. I can guarantee you the skill will be useless if it stays like this.
@ZOS_GinaBruno can you please bring this issue to the attention of the devs? Dizzy swing always was a very unreliable ability as it was, and it took skill and coördination to land it. Please don't let this playstyle stay in this broken state.
EDIT: Just tried it in a duel and it is impossible to land a hit. Well done ZOS!!