Hi Dan,
Can you please use Jetpack's Debugger module to send us some more information about your site? This report will include a bit more information than what you already provided, and so may be helpful to diagnose this.
1) Go to the Jetpack page in your dashboard.
2) Click on "Help" tab in the upper right side of the page and click the link for "Jetpack Debugging Center."
3) Click the link that says "click here to contact Jetpack support."
4) Fill in the description box and your name and email address.
5) Click the "Contact Support" button.
Thanks!