I logged on to my Spines/Fire Brute and can confirm that Burn + Blazing Aura is causing some -- but not all -- enemies to flee. I'm running Briggs at +4x8. Burn has always caused enemies to flee, like most ground patch powers. But the taunt in Blazing Aura usually held their attention strong enough to keep them from fleeing.
But since the recent patch and patch fix went in, it seems to be working differently. Burn still seems to trigger the "flee", and Blazing Aura still triggers aggro, but neither do so at 100% efficacy. The fleeing mobs do run far away, and they do eventually come back. But if I've moved away from their spawn point, they return to the spawn point, instead of me.
I don't know if this is Working As Intended or not, but it's definitely different from either the pre-patch and post-bad-patch/pre-fix behavior. I actually kind of like it, as it's a bit more challenging. I always thought it was dumb of them to just stand in the fire forever. But I didn't like it when all of them ran away, either. Now a few run away while most stay. This will take some adjustment on my part.