Surface Book 2 GPU Driver disappears randomly after May 2019 update

Thanks for the reply, Entegy. 

I tried reverting back to V1809 as soon as I found out that this was an issue, but it was well past the 10 day window allowing the reversion from v1903.

I ask respectfully, how are you so sure the issue is in software and not in hardware?  I actually own 2 of these devices, and the first one - purchased February last year - had reported device driver loading/starting issues for the GPU when it was first started brand new out-of-the box.  So I can attest that the GPU on that device didn't work initially, which was well before v1903.  It did eventually load and operate normally, although I did wonder why it should have had such a problem straight out of the box.

It is beginning to appear this discrete 1060 GPU was grafted onto a system with an integral UHD620 display adapter, and that maybe it wasn't such a harmonious union.  Nvidia's website support doesn't address issues with this particular GPU directly, and they appear to have distanced themselves from it.  I've attempted to use their latest driver's nonetheless in the hope that it would fix this GPU issue, but instead it caused a hardware lock error on the tablet.  Only by rolling the driver back to 388.08 did the hardware lock error go away.  So now I'm back at driver 388.08 for the foreseeable future, which isn't doing any good since the GPU drops out of the device driver list anyway.

So after all that rambling, what to do?  Ask for a refund?  After all, they (Microsoft) broke the thing.

Because this specific disconnect issue only started under v1903 and reverting to v1809 fixes it. Microsoft itself says it's working on a fix on the known issues page. If it was a hardware incompatibility, then it wouldn't be fixable by software, which would be a disaster for Microsoft.

Problems straight out of the box can happen, but there are a ton of firmware fixes downloaded once you connect to the Internet. Unfortunately, the Surface line has a bad reputation of poor quality firmware at launch.

As for the "union" of the two graphics cards, the UHD 620 is in the clipboard part and the NVidia card is in the base. They are separate. I'm not sure about a "hardware lock". I've been getting my NVidia drivers direct from geforce.com. I'm now on yesterday's 436.02 drivers just fine, apart from the disconnect issue of course. I did find a workaround for games, which is to play them in exclusive fullscreen. Doing this doesn't cause the disconnect, furthering the proof that the issue is in Windows, as when a game has exclusive fullscreen, Windows passes control of the GPU to the game. This does mean you can't ALT+TAB out of the game because the dGPU will immediately disconnect.

What to do for now? Wait it out. If you want to fight for a refund, that is your right as a consumer. I was warning against fighting for a replacement because all Surface Book 2s will have this disconnect issue under v1903 until a firmware/software update comes out.

It's possible we just received a silent fix for this.  Previously, I had the issue and could reproduce it 100% on demand by running Photoshop, Lightroom, etc. all at the same time.  I made the change to the nVidia control panel to prefer max performance and my Surface Book 2 has been stable (although battery life went down).

This morning, I got the update that nVidia released the 431.70 Studio driver.  I installed that and also checked windows update where I received KB4505903.  With those two changes, I reverted the control panel back to adaptive and have started up all of my most graphic intensive apps and have been unable to crash the system.  

Its interesting, however, that none of the release notes for either change mention this issue.

Microsoft support has recommended that I try Nvidia drivers directly from Nvidia before. Each time it usually resulted in problems including BSODs, etc. After escalating at Nvidia, they basically said Microsoft has a complicated system with the dual GPU and custom coded drivers and they only recommend using what Microsoft puts out. Unfortunately Microsoft only updates the drivers every 1-2 years even when there are major problems experienced.... so not only do the major problems remain, but so do bug fixes Nvidia puts out, AND major security issues.... It is crazy that Microsoft is not held accountable for putting out updates more often!

Yes, I know it is painful. Microsoft is not saying anything about the timing of
a fix. So you have limited choices. Other customers have posted interesting work
arounds, but I do not see verification from others that these work. We do know
that 1809 does not seem to have this issue.