I have a student who could not do the explore task. She would click on the unit and the section - and the screen was blank. Everyone else in the class could see it.
Solution (since someone else may run into this): she is in 2 classes of mine, and I assigned CSP to both. Her CSP class’ CSP was marked Visible. The CSA class’ CSP was marked Hidden. When I changed that to Visible, it worked fine. So, it is a teacher glitch (maybe) not a software glitch.