If you are experiencing missing pages when using a Varnish caching server with ProjectHuddle you might try and use the following rules to help prevent this:
In your Varnish Configuration:
// Tells Varnish to pass through on the website script loader
if (req.url ~ "ph_apikey") { return (pass); }
// Tells Varnish to pass through on the access token urls
if (req.url ~ "access_token") { return (pass); }