in 97 no green circles around of selected units

This is a known issue in the current version of the engine. As a workaround there's a widget you can use to give selected units halos (via f11) but you may not want to use to use it if you're on a slower system.

I have had this issue on all engines after 94.1. Boxes are displayed but not the usual circles.

Huj: Settings/Interface/Selection. Turn off Selection Shapes to get the engine squares, and if you want, you can turn on the other options afterwards if you like.