I have a student who cannot get into my Tinkercad Classroom he has been in it, it's no longer working for him. So, I deleted him from the class and re-enrolled him. I gave him a the same Nickname (his student number) and we got a "something wrong happens" message. So I gave him a slightly modified Nickname and received the same message. I did not ask him to delete his cashe. We are using Google Chrome on Macbook Airs.