I am not exactly sure how to reproduce this, but I wa in a race and it was just starting before the light went green, so I was sitting in the grid. I wanted to leave, so I hit shift+s first then quickly selected spectate. After that in spectate mode it only showed the blue gradient background instead of being able to view the cars in the race(The lag meter, messages, esc menu all showed up as normal). I joined and then went back to spectate, still the same blue screen, left the server and came back, still unable to spectate, after closing down lfs and reopening and going back to the server spectate was back to normal. My guess is somehow the making you wait before rejoining from the pit right at the start somehow caused this? This was on fe2r on the STCC 2 server.