OPerations Page Doesn’t Load

I installed the MainWP plugin on the website above (as the master site), but the Operations page isn’t loading. It still says “Loading…”

I checked this with SiteGround (where the site is hosted), but they said everything on the server and PHP.INI file (which I made additions to to ensure 300 seconds for the cURL turnout) were totally fine.

There was another “Dashboard self-connect check failed” warning (“Unexpected response (HTTP 500)”, but SiteGround said their hosting shouldn’t affect that.

Would you know why this is happening?

The page I need help with: [log in to see the link]