Multiplayer - 1 Step forward 2 Steps back

I’ve played Private Multiplayer with 12 Friends yesterday after the update. After a while some players could not see each other any more. The distance display went crazy. It seems that it began after Quick stops.
Also we could not see each others Designs on our cars.
Before the Update we often had early starts.

Other Things still missing:
-Forcing Standard Tuning and Upgrades dont works like in Forza Games before. Players must dismantle the parts from the car manually.
-When Upgrades are not allowed its not possible to load tunings, even when they are without any parts.
-Flying Start not possible.
-Manual Start Order not possible.
-Lobby Settings not saveable.
-Spectate Modus not available. But when less than two players ready the message asks for more players or spectators.
-Supereasy TCS cannot be disabled individually. Just on/off.
-Tuningoptions cannot be editet in lobby
-Upgrades cannot be editet in lobby
-No Testdrive in lobby
-Fuel & Tire consumption muliplicator.
-Unlimited Laps
-Distance display for races with ending after time with two numbers after the comma.

Yesterday we had another run of our League. Aigan some Drivers had the Problem of not seeing each other.
Is it possible that the Problem is caused by the enabled “Forced stock Upgrade and Tuning” Option ???