Just to add; another Windows 11 user with seemingly no issues.

Thank you for the reply, RsRaiders. You are understandable and after some more game time under my belt I'm getting a little more familiar with how sighting works. That said, I still have yet to see spot this mysterious and elusive "Sight Radius" icon which the manual makes reference to.

Trying to wrap my head around how unit vision works. On page 26 of the manual there is reference to a "Sight Radius" icon. I don't recall seeing this on any unit, ever. I do always see the armour, hitpoints, morale, actions and experience level icons but never this mysterious sight radius ...