If you recently had MS security updates installed on your machine you might have issues accessing K2 Management. See atached screenshot of what you might see.
Users are facing UI issues in application in IE11 browser.
NOTE: This will only occur when accessing the K2 Management Page from Sharepoint Context. Ie accessing from the K2 app in SP.
MS introduced change KB4012204
Windows 10 Version 1607:
Windows 10 RTM Version 1507
IE11 on Windows 7 and Windows 8.1
1. Restart Machine to which the Update was applied
2. Clear Browser Cache