Seasonal Championship achievements not popping

I’ve completed the “requirements” for the Summer, Autumn, and now Winter Seasonal Championships, and the achievements for none of them have popped. I’ve tried rebooting the console, deleting and re-installing the game and DLC, and even deleting and re-adding my profile to my console. No luck whatsoever.

What exactly are the requirements? Are we required to do only the three sets of races for the Championships, or are the other events, like the Co-op Championships also expected to be completed? Or, is this bugged? There are people on TrueAchievements that are having an extremely difficult time unlocking these when we think we’ve met the requirements:

when i first got them they popped at season changeover not immediately on doing them
and i hope you are doing them at highly skilled or higher difficulty

I’m doing them at the level the rules of the championship states. I finish first in each race and get three stars upon completing each championship. IS that not correct? If it’s not, then the game needs to change the description of the achievements.

I just re-ran them all on Highly Skilled, and nothing. So that in and of itself is not enough, or it doesn’t pop until Thursday which would be odd. I’m still of the belief it’s bugged until someone from Playground says otherwise.

All of mine popped straight away including the 50%. I don’t do the 80%.