D3D9 Present returns D3DERR_DEVICELOST even in Windowed Mode(!)

Question

Foreword

Since this appears to be a bug in the d3d9 Emulation on the Windows side, this would probably best addressed to Microsoft. If you know where I could get into contact with the DirectX Team, please tell me. For the time being, I'm assuming that the only real chance we have is working around the bug.

What

We're investigating an inresponsiveness found in the Game Test Drive Unlimited 2. Only when opening the Map and only when having an "RTX" Card (I think the most precise we got is GDDR6, because AMD also seems affected).

After long debugging, we found out, that it's not a simple fault of the game, but instead Present returning D3DERR_DEVICELOST even when having the game in Windowed Mode. When the Game is in Fullscreen Mode, it properly does the required roundtrip over TestCooperativeLevel and Reset, but after the next frame is rendered, Present has lost the device again, causing the Hangup.

Now I'm looking for pointers on how to solve this issue. While it's probably some internal state corruption of some sorts, it's definitely triggered by an API Call only present when rendering the Map in that Game.

We will try to dig into d3d9.dll, but my suspicion is that the error code just comes from some Kernel/Driver Call, where our knowledge and tooling ends.

Ideally I'd like to fuzzy-find the drawcall by just hooking everything and omitting random apicalls, but I guess it's just not so easy and causes a lot more errors in most conditions.

Also note that an APITrace we did, showed D3D_OK for every single call including EndScene, up until Present, so it's not as simple as checking the return codes. Trying to use Direct X 9 in Debug/Diagnostic Mode is also not really possible on Windows 10 anymore apparently, even when installing the SDK from June 2010

Thanks in Advance for any idea and maybe addresses to direct this problem to.