Sometimes when using K2 you may run across a claims issue. A realm entry not set perhaps. The following SQL query can be useful for troubleshooting these.

SELECT * FROM K2]..Identity]..ClaimAudience]
SELECT * FROM K2]..Identity]..ClaimIssuer]
SELECT * FROM K2]..Identity]..ClaimRealm]
SELECT * FROM K2]..Identity]..ClaimRealmIssuer]
SELECT * FROM K2]..Identity]..ClaimTypeMap]
SELECT * FROM K2]..Identity]..ClaimTypeMapping]

It's good information to include when opening a support ticket to troubleshoot the issue. Remeber that while running a select query like that is fine any changes made absent K2 will violate a given EULA so please do not make unsupported changes to your K2 DB.