The diplomacy rankings currently have me at #2 in approval, even though all of my planets are at 100% approval and have been for 100 turns. I doubt that any of my AI opponents have over 100% approval. Unfortunately there's no approval graph on the graphs button to compare to.
I can't at the moment speak to the tech power graph and ranking, since in my current game I'm #1 in both and have been for quite a while. In military though, I was #2 in graph and ranking for a while, until a combination of my buildup and my destruction of the Krynn fleets made me #1. For several turns the graph still had me behind the Krynn while the ranking had me at #1, so I suspect the graph might lag.
On the other hand there might be problems with both 
