I got a Razer Core X and tried to connect a RTX 2060 Super GPU. I got it to work a couple of months ago, but recently it stopped. Here I were able to see the GPU in the device manager and use it to play with.

Now I can see that the GPU is turning on and the fans are spinning, but it isn’t registered in Device Manager or any GPU driver apps. 

If I disconnect the Razer Core X, I can see that the device manager does refresh, so it detects a change. 

I would like to add that I have tried the following: Disconnect the Razer Core X and turn off the computer, then reconnect and turn on the computer. 
Used a different outlet. 
Took the thunderbolt cable out and repluged it (and verified it was a thunderbolt 3 connectiong).
I have taken the graphics card out and put it back in. 
I have tried to connect the monitor directly into Razer Core X, but it won’t detect or turn on either.

Should note that the RTX 2060 Super, does not have 2 entries for the power supply, so I would assume that only one is sufficient. 

Does anyone have any ideas on what can be the reasoning for the Razer Core X to not detect the GPU, even what it starts up and spins?