Just to clarify: As long as you use A6 mode and don't use shaders, the lighting and the effect of ambient looks exactly the same with all 3D cards, no matter whether T&L or not and what your computer is smoking.

With entity.ambient, it's the same as with most other features: If you don't get it to work, you'll have to blame yourself - not the engine, not your computer, and, as of recently, not even the documentation. I'm afraid there's no excuse left...