Yes, that is not what we have seen indicated on our analysis tools at all. This is a slightly worrying case, if something like that was able to slip past detection.
Here's what I wrote on the league wall, if you guys could do this it would be very helpful:
Hi guys, if you have more information about what happened, we need it. Please email support@igpgames.com collectively with all of your experiences in the one email if you can and we will look into why some people apparently couldn't join for the entire race. We were only aware of an issue logging in just before 6pm, but that sounds like something else. Our systems have not detected any faults that would produce such symptoms, so we're going to need to dig deeper to understand that.