Ok, GI Surface Detail wasn't what I was referring to though when I said "you are using GI". Whether GI Surface Detail is enabled has no effect on whether GI is used, it's just an additional enhancement when GI *is* rendered. As I said, if GI Relative Detail is greater than 0 and the Enviro Light is enabled, GI should be calculated. In your case it sounds like GI *was* enabled.
When you say you "did change the GI settings", do you mean those are the settings you used in the 1 second animation you've posted, or you changed to those GI settings since posting this thread and getting some feedback? It looks like the problem may be GI related so I would try GI detail 2, sample quality 6 next. You may also try slightly increasing atmosphere samples, maybe to 12, as this can have an effect on how Atmosphere GI samples are calculated.
- Oshyan