Um, interesting! There’s nothing obvious in those settings that would affect your students being able to see the activity.
From the screenshot in your original post, I see that Group mode appears to be set to ‘No Groups’. You have student self-completion switched on, but there are no completion restriction messages against the other activities, and there appear to be no other restrictions set.
I have no idea what’s going on here, although it’s likely to be something ridiculously obvious 🤨
I don’t think the activities are hidden - but can you check that?
What theme are you using? Have you tried temporarily changing to a different theme just to check?
Have you altered the default permissions for the student role?