As per the compatibility matrix, K2 Five only supports Internet Explorer 11 or Edge. If you are on an older version of Internet Explorer, then please update your Internet Explorer.
If you are already on Internet Explorer 11, then your document mode is likely set to Internet Explorer 10 or lower. To determine your current document mode please do the following:
You can change the document mode to 11 via the Developer Tools, and your Designer should work properly. However, this is not a permanent solution, as the document mode will revert back to its default value once you close the browser and open a new window.
One way the document mode can be set is via the X-UA-Compatible header. You can check if your X-UA-Compatible header is correct by doing the following:
If the X-UA-Compatible header already has IE=11 in its value, but the document mode in your Internet Explorer is still showing 10 or below, then please check with your administrators if they have restricted the document mode elsewhere, for example, via GPO.