So I just ran into my first major glitch in Dragon Age Inquisition. I was in a dialogue situation but could not select any options. Moving the analog stick did nothing and I couldn’t back out of the conversation. Luckily I discovered (by accident) that if I held LB it would bring up the action wheel and then while that was open I could move the stick and select an dialogue option from there. Weird, but just figured I’d share in case this happened to anyone else and you don’t want to load a save.
Best of luck!
avideogamelife 
just found this nasty bug out as well and found this same solution out by accident after raging and mashing all buttons on the controller. This solution works the same with ps4; hit L1 to bring up the action wheel and you will be able to choose dialogue from there by using the thumbstick as normal.