The straight walls mode indeed has this issue with the boundbox not showing up at any zoom level. Other things like units are also clipped. This problem is always there, but a lot more noticeable on higher resolutions. And since the original/gog versions of the game only support up to 640x480, for them it's not a problem.
If you feel 'normal view' is not an option for you, you could play the game in 640x480 mode and the issue should almost disappear.