Problem with navigation not working across sibling routes, Epic Stack, flat routes

[tall igloo]

are the URLs correct? are you using relative paths?

relative paths will behave differently depending on whether you have a trailing slash in your URL at the moment

when you click upload on /foo/abc123/ you go to /foo/abc123/upload but on /foo/abc123 you go to /foo/upload, which might be a 404 and maybe you have that set up to redirect somewhere