I recently had an issue with Tamper Monkey, jQuery, subdomains. You can view the issue here:
tampermonkey.net: subdomain + jQuery issue
Basically, my page would load jQuery plugins when I hit the page directly from my site. But, if I hit the page via a subdomain off the website, the plugin would not load. Any javascript that used that plugin would err as if the plugin did not exist. When I disabled TamperMonkey and reloaded the page, everything would work through the subdomain again.
You can try it with this tech test. This is without the subdomain:
http://example.digitaleagle.net/subdomain.php
This is through the subdomain:
http://example.digitaleagle.net/subdomain.php
You should get alert dialogs when the page loads and when you click the button.
The fix is to use the Beta version of Tamper Monkey. This latest version fixes the bug. You can download it from here.
Also, just FYI, here is my original thread asking for help: