Likely this is happening because you have installed standard drivers direct from Intel and/or NVIDIA. If custom drivers are necessary to support automatic switching between GFX solutions, loading the (non-customized) standard versions will prevent this feature from working.
I suggest you go back to the latest versions of the drivers that are provided by your laptop vendor. If you need later drivers in order to avoid some particular issue, you need to ask your laptop vendor to produce versions of these later drivers that include their customizations.
Hope this helps,
...S
