Multi-Site Issue [main site fine but subdomains get error message]

I’m experiencing issues with using microthemer on a subdomain site. There’s no issue with my main site.
I have deactivate pretty much all plug-in’s and the problem still persist. I also moved from Firefox to Chrome and the problem is still there.

This is the error message I’m getting
Something’s wrong
Loading WordPress site took more than 20 seconds. A JavaScript error may be preventing the action from completing. Microthemer hasn’t discovered any yet though.
QUICK SELF-HELP TIPS
Search for JavaScript errors using your browser’s console. (for the most reliable/detailed debug info.)
If the JavaScript error URL hints at a particular plugin, disable it. If the Microthemer problem goes away, you know the source.
If you have no clue, disable all plugins. If the error goes away, it’s a case of re-enabling half of the plugins, then half again until you zero in on the culprit.
Plugins that concatenate, minify, or re-order CSS and JavaScript cause problems sometimes. Try playing around with the settings of such plugins.
If plugins aren’t the cause, it’s likely your theme or Microthemer itself. At this stage you might prefer to send us login details for your site via our secure contact form. If we can’t isolate the issue from there we may ask for a backup of your site to test on without interfering with the live version.