I have students that are using code.org at home. They have logins that we are using in class. When one of my students tried to code at home it did not save her progress.
Maybe put in a bug report or have the student whose progress did not save put one in. It could be a glitch.
My guess is something else that may happen is the tool loads using an internet connection, but if the student ever loses connection meanwhile, the tool continues to operate but isn’t able to save progress. Hard to tell, given we might not know the internet connection conditions the student is working under.
I have one student having the same issue.