Seem to be having problems with heavy attacks with controllers since Summerset. At first I thought it was just a bad wire on my controller so I switched to wireless. Same problem
Went over to my buddy's place who has two brand new controllers and have the same issue on his comp in game. So then I thought maybe they were forcing us to weave light attacks now.. I searched Summerset patch notes and didn't see anything about that, however I did see they said they fixed a bug that made it so holding heavy attack button would make it so you didn't heavy attack.. Seems it may still be bugged on controllers. Sucks when you have a heavy attack build but it won't heavy attack most of the time..