I have looked at it now, and found the reason.
We don't run the auto-challenge-checkers for trials. It's quite a few accounts that activates the trial, and not all of them becomes paying members. That would mean a lot of computer power spent on those instead of those who actually paid.
The problem here is that the code doesn't look into the membership record into the future to see that they actually have paid.
To be clearer. You activated your trial on the 21st of April. 10 minutes later you bought a membership. This should all be fine.
But the auto-challenge-checker system still thinks you are a trial until it expires on the 1st of May (7 pm UTC), when you are becoming a "real" member.
I have left a note about that we should look into this and make it smarter.
Meanwhile, I have started a "special version" (aka hack) that runs on only you, so some should show up soon.
The auto-challenge-checker system is designed to only run a few hundred on each user, then jump onto the next one, so everyone gets their share of time. It usually runs for 2-5 minutes per user. With time, when the job has been started several times, the number of challenges checked has expanded. It starts near your home coordinates. Or in case when the site don't know them, it starts where it guesses that you live, calculated from your finds.
