I recently installed OSMC on an AppleTV.
I could not find my trusty aluminum remote so I unwrapped a NEW white remote (I have a box of em I bought cheap). None have ever failed out of the box yet, however this one did not control the AppleTV other than Pair, unpair , & reboot. Other remotes DO work on the new install.
As I recall these remotes have a unique ID that goes in the IR to ATV.
So this leaves me wondering if I isolated a remote whose unique ID is not recognized by ATV client.
I will see if I can look into getting ATVclient in the test mode to see what I can see.
Of course I could have just got a dead remote, but as it was brand new it seems unlikely, and also the pair unpair and reboot functions do work