Moto
I've just done a fresh install of OS4. After the recommended cold boot I had no GFX card screenmodes as you are reporting. This was because the driver in Devs/Monitors was not set up properly. It was the driver in Storage/Monitors which had all the GFX card screenmodes listed in its tooltype.
I suggest that you try moving the driver that is now in Devs/Monitors elsewhere, and put the driver of the same name from Storage/Monitors into Devs/Monitors, as it solved the problem for me.
(A reboot then took me straight into 800x600 16bit)