Update: i can confirm that at least for some of us the issue is DX12 support. I changed the API from DX11 to DX12 via the in game menu. After quitting WoW i no longer could log back in. I press play and get the “game is running” message without the game starting ofc.
This is clearly on Blizzards end since until last night i WAS using DX12. Which is the default API for my GTX 1060 6GB gfx.
The method to resolve this is: world of Warcraft -> retail -> WTF open the config file with notepad and change gxApi from “D3D12” to “D3D11” and gxMaximize from 1 to 0.