I'd engage in the following troubleshooting process:

1. Get another quality passive thunderbolt cable. It is possibly that both your passive cable and active cable aren't working properly. You want to make absolute sure it isn't the cable. Having a third backup cable is useful anyway.
2. Also check your power cord to the power supply. It is very unlikely that this is the problem, but just to be exhaustive.
3. Open the box and clean out any dust if it is dusty. The 1080 Gaming Box is very easy to open up in my experience. Just a few screws, you pull off the external casing very easily and you have access to the internals.
4. Same thing with the ports themselves make sure they're clean.
5. Try an external power supply if you have one available. The connections in the Gaming Box are standard 24 -pin to the eGPU's thunderbolt dock and 8-Pin/6+2-Pin PCI-E to the GPU. It isn't much different from connecting a PSU to a motherboard + GPU. If you don't have a spare PSU to test then you might want to buy one that would fit in the enclosure at this point. This is the one that is already in there, but with all of the extra cabling still intact.

If none of this works, then it is unfortunately probably the thunderbolt dock itself and that would need to be replaced.