I had this exact problem - I wanted to know how to find problems. I'd tried Customer Development and concluded that interviewing potential customers is not the way to go. People don't walk around with lists of their biggest pains and interviews become easily biased.

I got then introduced to Amy Hoy's Sales Safari technique where instead of interviewing people you observe them. You find out where your audience hangs out online and listen what they talk about. After you do this enough you start to see patterns. And these patterns are the raw material for figuring out problems to solve. I highly recommend Amy's 30x500 course.