Symptoms
It is found that new add domain users cannot access the workspace tab with permission setting.
Diagnoses
The web.config of workspace has not add the AD string after new domain added to K2
Resolution
Please backup the web.config before making changes.
https://help.k2.com/onlinehelp/k2blackpearl/ICG/4.6.7/webframe.html#After_AddingMultipleDomains.html