That appears to be a feature of Kinsky. If I access my twonky server from the same device, using ‘by folder’ in Kinsky and BubbleUPnP, I get alpha in the former, and numeric with the latter.
There are some tips on optimising for clients here, but I’m not sure they’ll help.
I liked Kinsky, but they broke it so it won’t auto-advance to the next track on non-Linn DMRs, deliberately or otherwise.
