yesterday in a race from a community a friend of mine (moneypizzle) didnt seem to see atleast 2 cars for the entire 30min race. i recorded some of his footage. P2 takes off before race even starts and doesnt reappear for the entire race new P2 has collision with real P2(invisible) in the left hander, i remember seeing this in my mirror(i am in p1) from what i could gather other ppl saw these cars fine and moneypizzle wasnt lagging for whenever i saw him. i have also noticed this in the past when either i couldnt see my friends, but they would still get hit by me. or the other way around. (since collisions are purely clientside, the person not seeing the car wont experience a collision if there isnt a car for him) just wanted to push this out so this gets fixed at some point.
There is indeed a sync issue in multiplayer. For me I used to see it after 1 to 3 hours in pc2 on a dedicated server track day session where new players would stop loading to me. Same happens in ams2 by the way.