It seems it's indeed buggy!
I have checked profile of some users, and the results were inconsistent...
The number of games in their Opening stats didn't match with their actual number of games, and for some users, no game was displayed in their opening stats at all.
It seems that's the case even for users with paid membership.
I was curious on what my most played openings were and how many times I played them. However, if you look at these stats, it only shows that I've played the King's pawn opening once as White and the Kings Fianchetto opening once as Black? Is there a way to fix this, and if not, are there any other tools I can use to find this out?