Symptoms

This customer is having issue similar to what is described in this KB, http://help.k2.com/kb001627.aspx.
https://community.nintex.com/t5/K2-Archived-Articles/KB001627-Known-Issue-when-using-OAuth-with-On-Premises/ta-p/218760 
Random users receive the following error when interacting with SmartForms residing in SharePoint 2013 Page.
“Access denied. You do not have permission to perform this action or access this resource….”
The issue sometimes is resolved in 15 minutes by itself. The issue could also be resolved by deleting OAuth token in oAuthorization].zOAuthToken] table per the above KB. However the issue will reoccur. Clearing user’s browser’s cache does not resolve the issue.

 

Diagnoses

When asking user with issue browsing to URL: https:///_api/SP.UserProfiles.PeopleManager/GetMyProperties, we noticed that the following properties are missing value:
SPS-ClaimID
SPS-ClaimProviderID
SPS-ClaimProviderType

 

Resolution

The issue was resolved by performing a one-time full synchronize for User Profile Service in SharePoint.