Glad yours started working again cap10morguen 
Unfortunately mine still dosent work , I thought I’d try my son’s console but that done the exact same thing . His other games work fine with it , even party chat but for some bizarre reason forza dosent work this is very strange , and I can’t see forza fixing this as not many people have complained about it 
I think it might just be a random issue that will hopefully “fix itself” soon. Kind of like how the issue with only hearing half the lobby sometimes happens and sometimes doesnt. Could be related to other issues they are having that might get fixed (generic server issue or something like that perhaps?) I’ll keep my fingers crossed for us both. (Just because mine worked last night doesn’t mean it will tonight)
Hopefully that’s your sorted for good,
if yours lasted roughly a week I hope mine is resolved tomorrow ish ( won’t hold my breath though lol ) as it was last Friday when it all started to go wrong