I would really appreciate it if someone would do this VERY quick little test to make sure I'm not going crazy. However, you need to have a new enough card that it's detected as "...T&L device detected." Otherwise, the engine's going to default to A5 mode--and I'm already certain sure it works correctly in A5. Here's a sample of how you can tell if the engine thinks it can default to A6 mode:
Here's the test:
1. Hollow a large cube.
2. Add a very bright light.
3. Add any model and check it's "unlit" box (leave ambient at zero).
4. Compile and run. See if the model is ignoring it's environment and is dark.
It works correctly in A5 mode, but not A6. Here's a shot that shows how the barrels are correctly dark when I force it to A5 mode, but simply turning on A6 mode leaves them full-bright: