Hey Guys,
I have a problem with the season championship coop races.
I won the race at least 5 times now and i never got the super wheelspin.
On the map the event is still available so it just dont recognize its won.
I dont know what im doing wrong or if its just a bug.
I hope someone can explain me whats wrong or having the same issue.
Thanks guys
Same happened to me.
Failed the first 2 attempts because of my team. On my third attempt the team only consisted of one other player. Went on and won the series, but never got any rewards, and the championship-icon on the map still says “co-op available” instead of “completed”
ok then i know im not the only one with this issue at least. 
please tell me if you find out how to do it…
thank you
Both the online PVP and Coop Seasonal Championship rewards have been broken since launch three weeks ago, and are still not being investigated or even acknowledged.
Solo is the only one that completes / works and gives out rewards as intended.
See also:
https://forums.forza.net/turn10_postst135302_Trail-Seasonal-Championship-not-giving-out-rewards.aspx
https://forums.forza.net/turn10_postst133914_Seasonal-Trial-win-conditions-bugged.aspx
https://forums.forza.net/turn10_postst135489_No-super-wheelspins-for-seasonal-coop-championship--and-other-issues.aspx
https://forums.forza.net/turn10_postst136934_Seasonal-Coop-Championship-broken---no-rewards.aspx
Submit support tickets:
https://support.forzamotorsport.net/hc/en-us/requests/new
Yes, they are not working. Won on expert and very experienced and still nothing! The problem exists since release! Nearly everything online related is not working in this game!