Today’s Daily “sparkling clean” does not work for me. I’ve posted many clean laps in circuit rivals and point to points. I’ve won them. No matter what I do it won’t complete.
I have searched here for anyone else having this issue but as usual I can’t find it.
Same here 
Ah the joys… 
Try to make a dirty circle and even lose. Also, try to use a sprint (from point to point) instead of a circle.
And check out this post and a couple more below, in the same place.: https://forums.forza.net/t/festival-playlist-events-and-rewards-apr-28-may-5-summer-s7/546821/104?u=lsd51zen
Happened to me aswell, running against a dirty lap on a point to point track worked for me
I ended up getting it. I had to beat my own time in Emerald circuit. Forza is fun, if you like puzzles.