It's hard to tell what comment you were responding to. But if this is the last time you flew Frontier, then your miles may have expired because you did not have any activity on your account for 6 months.

That's not to say that Frontier doesn't have issues with the new system. My last flight was sometime in February. But when the new site went online, it showed me as having not flown this year. Then, a week or so later, my account showed a whole bunch of YTD segments and miles that I didn't actually fly.