I'm using the clean theme, and when you have 2 sections hidden, both of which have activities also.
As an instructor when you go and open the action menu, on the hidden section above the other section, the action menu's absolute positioning is changed because opacity causes a different z-index context.
So even though the action menu's z-index is set to 1000, changing the opacity on a whole section causes that z-index to be ignored when rendering the sections.
Because of this, it makes the action menu unusable. So for instance I can't click the delete button in my image below
Screenshot attached for a visual representation: