I have found that my Page Assignments are not importing (from a static resource pack) when they have specific Applies To users.  The JSON in the static resource has a reference to both 
skuid__Assigned_To_User__c and to 
skuid__Assigned_To_User__r and SFDC doesn’t like the conflict and generates the error “Cannot specify both an external ID reference Account__r and a salesforce id, Account__c”. 

I went into the static resource and removed all the skuid__Assigned_To_User__r references and the page assignments then import correctly.

Seems like a bug in the Package All Page Assignments code?

Thanks!

- Chris