When you edit the section title and turn off 'Use default section name' but don't type any text, save then go back then 'Use default section name' is ticked, however the database entry for that section in the table 'course_sections' - 'name' field is empty and no longer 'null' thus the logic:

{code}

// When on a section page, we only display the general section title, if title is not the default one
$hasnamesecpg = ($onsectionpage && ($section->section == 0 && !is_null($section->name)));

{code}

in '/course/format/renderer.php' method 'section_header' fails.  Therefore when the course setting 'Course layout' is set to 'One section per page' and you click on a topic then you get the section 0 title 'General' even though 'Use default section name' is ticked.