Categories wont expand when pressing the "+"

I'm wondering is anybody here could let me know what I'm doing wrong?

I can move the categories up and down.
But they wont expand when pressing the "+" to create a sub category.

I have tried to uninstall and re-install, same result.

Running version Osclass 8.3.1
Godaddy hosting.

Any help would be highly appreciated

Any error in browser console?

That non-expanding "+" button is almost caused by a background AJAX request failing, which breaks the page's javaScript. sometimes as you have said you hosting your website on GoDaddy hosting, this is also usually triggered by their strict Web Application Firewall (ModSecurity) which blocks the request or even by the hidden PHP warnings corrupting the data structure,
According to my experience i request you to go forward with these troubleshoots, they may help you
First.. identify the Error using Browser Console
Second, Disable MobSecurity on your cPanel
Third, Turn Off PHP Error Log

and also you can Clear the Osclass and your Browser Cache

Failed to load resource: net::ERR_BLOCKED_BY_CLIENT
index.php?page=market&action=themes&product=theme&pattern=&type=free:1 <meta name="apple-mobile-web-app-capable" content="yes"> is deprecated. Please include <meta name="mobile-web-app-capable" content="yes">

Failed to load resource: net::ERR_BLOCKED_BY_CLIENT
index.php?page=market&action=themes&product=theme&pattern=&type=free:1 <meta name="apple-mobile-web-app-capable" content="yes"> is deprecated. Please include <meta name="mobile-web-app-capable" content="yes">

Don't believe this has any impact