Because endnotes are considered a level 1 heading, adding endnotes to a script without any other section headings (i.e. just scene headings) will cause everything to collapse except the endnotes when cycling the outline, which is weird.
Endnotes can be considered "depreciated" or more accurately "an idea that never really took off in Fountain" and will be removed in favour of something like https://github.com/rnkn/side-notes
Because endnotes are considered a level 1 heading, adding endnotes to a script without any other section headings (i.e. just scene headings) will cause everything to collapse except the endnotes when cycling the outline, which is weird.