Fireblast and Impact = Broken

Impact: Gives your damaging spells a 5/10% chance to reset the cooldown on Fire Blast and to cause the next Fire Blast you cast to stun the target for 2 sec and spread any Fire damage over time effects to nearby enemy targets within 12 yards.

This is severely broken. I honestly wanted to try Fire PvE but this only worked about 20% of the time in my first dungeon. Anyone else have this issue?

Edit: Changed the title to make the subject a little more clear.
You have to be in combat with the targets you're spreading the DoTs, so just Blastwave them.

And also, from the most recent patch notes they said that it was bugged.

Bug Fixes
Living Bomb’s interaction with Impact has been cleaned up, and should no longer sometimes fail to spread Living Bomb to new targets. We hope.
I havn't really ran into an issue. I actually think it is quite sexy when I have LB, Pyro, Combustion and Ignight, then hit that impact proc.

MmMmMmm..

To answer your question, I have not had(or noticed) an issue.
Deleted by Iin
I think it depends upon the zone somehow.

FL I had issues all the time. (haven't checked since patch)
Normal cata heroics are guaranteed to have a few bad impacts.
Trolls are a little better then normals.
HoT heroics haven't had a noticeable one yet.
DS I haven't had a single bad impact.

It is such a weird bug.
I am still having this problem too. I have noticed that in fights and from raids. I can spam flame strike to my hearts content, or do blast wave on cool down, and more often than not, my impact either never pops, or it does pop, but fails to spread living bomb to other targets opposed to the one that I am striking down.
I wish they'd just let Fireblast auto-spread dots. It's not like you cast it in PvE unless that's your intention. Leave the stun/cd-reset as a proc.