I have this problème too, same os but Hw is Nuc dc3217by.
I performed the test in one of the Intel® Compute Sticks we have in our facilities.
It worked fine.
What I did:
1. Download and install the host app
2. Tested the system with the keyboard and mouse connected (wired).
3. Reboot and removed all peripherals (keyboard and mouse).
4. As soon as the Intel® Compute Stick booted, I the phone app recognized the device and I was able to see the pointer.
What could help with the scenario:
-Please make sure you have all windows updates installed in your system.
-Re-installing the host app and the application in your mobile device could help.
-Make sure you are using the latest BIOS version in your system.