Submitted this issue to bug reports: http://us.battle.net/wow/en/forum/topic/7415794384#1
Howling blast not applying Frost Fever debuff
"Pretty much self explanatory. I'm definitely hitting the targets with HB and I can see the Chillblains debuff on the target, but the Frost Fever debuff isn't always applied (to the primary or secondary targets). Can someone please look into this?