Last night, GMT time, I had this exiting a rivals event back to menu where it shows you position in results from leaderboard.
Just timed out there giving message as title row and suggestion to try again, and going back to FM7 main menu.
One thing to just return and letting you Retry - but it exited.
Was on Forza Crown 1-3 rival events I went through. Maybe 1500 results so far on leaderboards, which does not seem like a massive load on system.
Just happened this time for me, but only had game for 2 months.
A bit concerned if Turn10 already has performance issues.