In K2 5.1, when accessing the Roles page in Management, the next button might be greyed out and/or not clickable.
If you hit the User Role SmartObject - List Role method using the SmartObject Tester, it returns all roles correctly.
The same behavior also appears if you hit the form at runtime (using the Service account or any other account).
Edit the Web.config in the Smartforms Runtime Folder.
1. Find the key "SmartObject.RuntimeListViewRowCount"
2. Update it to False like the following: