Understanding Frequency Per User Breakdown in Insight Reports

I feel like I'm missing something about the Frequency Per User breakdown... if I set it to Per Interval it works as expected but if I set it to After Step 1 it does nothing... I thought maybe it's not supposed to work for insight reports and only for funnels, but if I change my report into a funnel the option doesn't even appear, I can only select Between Funnel Steps , so it's clearly meant to function in the insight reports, but doesn't seem to work