Froth stopped happening?

I've had my Bialetti 2 cup induction model for a few months and other than a couple of times when it failed to extract it's been great. However, for the first month or so I was routinely getting froth/creme when it began to come up, and then for the last month or so it's absolutely stopped doing that at all. I've tried lowering the temp and under packing or over filling the puck, neither seem to help. Any ideas? I haven't changed coffee brand either (preground Columbian)