I am finding this out. The sensor was kinda ICE'D over. Was a wet snow. Just SUCKS in my honest opinion. And correct me if I'm wrong but the owners manual says nothing about this flaw in their AEB detection system.
Just like the frost covering your windshield in the morning allows you not to see out it also must see to function. Cake it with snow/dirt or mud and there is no way it will work. It's not voodoo you know. 
By the way, connected to Blue Link to complain about the issue and the lady connected me to the Genesis department and didn't realize that they had closed for the day. @HYUNDAI - I hope you read this message board and realize that the little things on a 50K car make or break customer reviews.
Bluelink is a service offered by Hyundai and not especially for you because you paid more. There are real people behind the Bluelink service and just like you who thinks the AEB system is infallible they also make mistakes sometimes.
Last but not least, let a driver have AEB toggled off when the car starts. I know HYUNDAI wants to taught AEB (Have you seen the car ad where they jump out and all the cars stop automatically when the lead car does....) but I as a sensible driver do not want nor need AEB, nor the hazzard sensor flashing at me when AEB is ICE'd over. Should I expect this every snow day here in COLORADO...