Something was wrong with this week event: all races were open at first but then had a date to start.
Yesterday it appeared a new event "week sprint champ" with 7 different races. All of them where open and free to play, so I did till I run out of gas.
This morning I tried to finish the rest of the races, and with each try a "???" message was showed, adding it was impossible to race.
This evening all races appear closed except the first one, but all as passed.
I've tried to put some screenshots together in only one file (about 1MB) but I wasn't able to upload it.