Pega PRPC 7.2 (now 7.3) has been deployed at a client site implementing several features. Few UI screens leveraged the OOTB Control for displaying Radio Buttons encountered this erroneous behavior. It was seen that clients using Internet Explorer (particularly MSIE 11) were unable to see the radio buttons for selection.
Upon analysis, configuration issue was found in the operating environment. On Windows 10, the html element in the document has "tablet" class in it, which has specific styles for radio buttons. This affected the rendering on computer browsers to correctly display the radio buttons, causing them to hide.
To fix this, UserWorkForm HTML rule was appended with the following style snippet.