It just came to our attention (thanks @sparkweb
!) that manually triggering the subscription errors datafeed has not been working since we moved over to our failover system. The first error in our logs is from 10/4/2012. We fixed the issue so if you click the "Click here to refeed your Subscriptions XML Datafeed" link under the advanced menu in the admin, it should now work as expected.
We're very sorry if this impacting you negatively. We tested quite a few things extensively but this one action within the admin was missed in our testing and will be added for the future.
The daily, automated subscription datafeed was not affected.