Start a new sub profile and the problem goes away. As I have said in the past I know many people with this issue and he have met randoms in lobbies with this issue. Finally I myself now have the issue. I think it has to do with the amount of tunes and paints you accrue and if approach or you are at the limit. Sadly Turn 10 refuses to admit the issue or provide any fix. To make money you can easily auction cars from one account to another. I bit of a pain to setup but it will be worth it if you do experience this. As a bonus anyone who has blocked you in the past will no longer be. Blocking is only supposed to block communication and not matchmaking anyway. This will fix that too if you too have been blocked by people because you are too fast, too clean, or god forbid asked them to stop cutting or ramming.