I am having 404 error issue with 2 subcategories  open due to an added ?Itemid=0 at the end.
 
  I could only find the issue with two subcategories and the Overview/UP button on the same category. 
 
 The plugin  in the articles have no problems with links. 
 
  Category with subcategory issue here https://www.kidsactivitydownloads.com/index.php/public-downloads/category/165-fish-and-wildlife-activities
 
 I have tried deleting .htaccess, rebuild links, refresh permissions, ran ACL Manager diagnostics, reinstalled jDownloads Version 3.9.7.2 and Joomla 3.9.24
 
 No sef plugins installed and setting in globally is on default.
 
Any suggestions would be very helpful before I recreate new subcategories and redirect all the links to the new download folder.

Hi
Yes I see what you mean!
Do you have a jD 'List All Categories' menu item?Think unlikely but have you any overrides?
Can you also please run a 'Check Download Area' on the jD Control Panel
Colin
PS have sent you a PM.