Minim Server - BubbleUPnP - Cabasse Abyss – Playback doesn't work

[bubbleguuum]

That BubbleUPnP log file is playing to the local renderer, not to that Cabasse renderer. So this log file does not correspond to the MinimServer log where that HEAD request is coming from the Cabasse (whose ip is 192.168.188.59).
In the minim log, I can see the HEAD request but the fact that there is no subsequent GET request from the Cabasse to get the stream means that there is something it does not like in the HEAD response and stops there. Maybe it does not like the value of the contentFeatures.dlna.org header. DLNA renderers can be super picky.
I asked OP to send me a log file playing that FLAC stored on his Android device to the Cabasse (which I was told was working). It will allow to compare the HEAD response.