dGPU disconnect after switching to iGPU

The MX150 drivers in my Dell Latitude 5401 are disconnecting shortly after i close my games. I know the MX150 has been disconnected because when i start a game again it says: device not connected. When i go check in Device Manager the MX150 is still there without an error code. When i turn it off + turn in on again, Windows gives me error code 31: This device is not working properly because Windows cannot load the drivers required for this device. (Code 31)

If i don't turn off the MX150 i will 100% get a BSOD when shutting off Windows or restarting it. After restarting Windows, the MX150 is working fine again and drivers are found, until the problem repeats.

I can reproduce the problem very easy when going to Nvidia Control Panel Settings and let the preview window (the spinning Nvidia logo) open for a while. This forces the system to use the MX150. After 1 to 2 minutes, mostly when clicking out of focus (for example opening the Windows menu) the screen goes black for a second and the preview window is blank, no spinning logo anymore. That's the moment when the MX150 drivers have gone missing again.

I don't think it's a hardware problem because i can game for hours on the MX150. The problem begins when i quit gaming and the system switches to iGPU again. When this switch happens, the MX150 gets lost and won't recover until i restart Windows with a BSOD.

Seems something is wrong with Optimus or the MX150 drivers? I have tried all MX150 drivers from the Dell website, Microsoft Update drivers and Nvidia Original drivers. With all of them i can reproduce the missing MX150 through Nvidia Control Panel preview window. 

How can i fix this issue? I don't want to lose my connection to MX150 every time Windows switches to iGPU after gaming and have a BSOD because of that.