Same with me. If I try and control the volume from the Spotify App the volume increments quite big for some reason (Android), but not going from from 20-85. That’s weirdly extreme. More like increments of 3/5 instead of 1 via the Naim app.
I use an iPad mini for my Star because the controls on my phone are very small and it can be difficult to adjust the volume in small steps. I use the remote for volume 99% of the time. I do get artwork freeze about once every ten days. An unplug wait for twenty then start again clears it.