this might happen due to the scaling that is set in Windows 10 for text, apps and other elements. The console lacks the ability to handle the scaling other than 100% and especially with UHD displays the windows will look like this. Just reset the scaling to 100%, log off and log on and the window should be all right.
Try it out and let us know if it works!
Thanks for your response.
I had thought of that. I am using a MS Surface pro with two additional screens. The additional screens are not UHD and scaling was set to 100% but I still got the issue.
It turns out that the console must be affected by the scaling of the main screen rather than the screen the console is displaying on. Changing the main screen to one of the standard definition screens resolved the problem.
Thanks for your help.