Volumio / Squeezelite / miniDSP volume mismatch

Apologies, I just raised this on Github but perhaps here would have been a better place.

I have a miniDSP SHD which has Volumio. I have installed all the latest firmware and updated to the latest Volumio version.
I’ve installed the Squeezelite plugin. I have the Squeezebox APP on android and also a Squeezebox Duet control which allows me to select tracks/playlists, skip forward/back, play/pause. This all works seamlessly.

Volume control is the problem. The SHD volume can be changed from -127.5db to 0db in 0.5db steps. When I change volume on the App, the miniDSP volume is changed seemingly randomly (anything from 1db to 5db!). I’m assuming this is because values do not correctly correlate. The APP has a 0-100 scale so 50 on the App would equal -63.75 on the SHD which simply doesn’t exist, so the the SHD jumps to the closest available value (-63.5db or -64db). I’m guessing.
Also, if I change the volume directly on the miniDSP’s using the rotary volume control I can change values in 0.5db steps but as soon as the playlist moves to the next track, the volume jumps up or down by a few dbs.

Any help or advice would be greatly appreciated as I’d really love to control all functions from the Duet Controller since it can be operated by touch.
Thank you,