Achievements issues - Possible solution

[Delta 66]

As far as I can tell from my experience. Achievements take into account all active profiles.

For example I get the 100 Counterattacks achievements with 27 counterattacks for one profile, and 72+ from a second profile.

The thing is, this may also be the reason for the All Belts without Knock Down achievement not working, although you have completed all three championships without KD.
Make sure, that no other profile have KD too.