Mac user here on iMac and DX7s for over 3 months. I have had the same problems as @rickymiester and @mi-fu, and mi-fu's solution has worked for me also. I will watch with interest if Topping has any reply to rickymiester's inquiry.
I also wanted to report on interesting findings on using...
That is true, but all those defaults settings are the same settings available on the remote.
Edit: Except for the factory reset setting, which can only be done using the volume button on power-up, AFAICT.
I'm not sure what you mean about directional commands. With my Harmony remote, I can get to all the setup items mentioned in the manual. The commands on my remote are:
FIR (for filter selection)
Display (for display brightness)...
I have a DX7s (without the remote) and all functions are accessible from the volume button. The instructions are in the manual. Having successfully tested all the volume button functions, I took an unused Logitech Harmony remote and added the Topping as a device. The Harmony remote works perfectly.