The display of instances can depend on their distance from the camera. Check in the top menu if you have selected
display->Show detailed ecosystems near camera.
If so, the instances you paint further away from the camera will be represented by a dot, those closer will have full display. If you move the camera closer to those the display will change dot->full.

Also, in v6 inf there was a section 'Display options' in the general tab of the eco material editor. It was possible to chose the display quality (wire, box etc) and if you want 'full quality near camera'. This section seemed to have disappeared in v7complete. I wonder if it is there in other versions  - v7 inv, v8 complete or inf...
The silly thing is that you can still specify these selections if it is a global eco system. Anybody see the logic in that?
If it exists in your version you can change the radius of what's considered 'near' the camera in addition to choosing the display quality.

Anyhow, bottom line, you cant expect to always see all instances in the 3d windows - that may become too big a task, so just seeing fully those close to the camera seems a reasonable idea.
You can always do a quick area render in preview quality to see any of the other instances if you need to.
(and if you dont have many instances, you can convert them to object and than they will be fully displayed whatever the distance)

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
http://artpearl.redbubble.com/