What doesn't work: When you add a text label to a course in grid layout with list elements missing the surrounding <ul></ul> tags, all subsequent sections are not viewable to users any more and flow outside of the red box in editing mode.
How to reproduce:
1. Create a course using the grid layout
2. Add a text label to the first section. Edit the HTML source with Atto. Create list elements (like "<li>element</li>"), but without surrounding them with <ul>...</ul> tags.
3. Save the text label. You will notice that already the site formatting in course edit mode will look messed up now. The subsequent sections are now no longer in the red box.
4. Add some content to a subsequent section.
5. Turn off course editing and try to access the content you added in step 4. It will not display.
One of our customers had this happen on several courses. I don't know why the <ul>...</ul> tags are missing (perhaps this used to be a bug in Atto?) The courses are old and used to be displayed correctly despite the faulty HTML.