I have been through every driver release since the Vega launch and tested with both Vega 56 and Vega 64. Using any driver newer than 17.9.3 then Stellaris will no longer run, the game hangs at the start game screen where you select a new game or a load. This is ONLY happening with Vega, the newer drivers work fine with a 580, 570, 480 and 380 card, all tested. Attached is a screen shot showing the location of the hang up. The game will allow you to click new game and then go no further. You need to go to task manager and kill the task to get out of the game.
This creates a real issue as some of the newer games, such as Wolfenstein and Prey will not run correctly without the newer drivers.
Again let me stress this is ONLY with Vega cards and driver newer than 17.9.3. I have tested with newer drivers on older cards and the issue is not there.