I guess they had some technical troubles. In the beginning of the contest, I was unable to submit or test anything for quite some time. It gave me errors or just nothing happened for several minutes after I hit submit button. That was quite annoying and distracting. Not sure how common this situation actually was.
Yes, I had similar problem.
I cannot submit for 10 or more minutes.
I do not know what happens on their servers.
In addition, such problem might cause the final rating unfair.