I've been at this for at least two years and none of the players you can find on Android is really happy with the PMS (they are not patient enough). The only solution I so far got working real good i my own "download stream" method which basically temporary downlads the file and then the player reads from the file (the whole file isn't downloaded). VitalPlayer can cope with this scheme.
I've only had trouble with 1080p videos which I believe to be a transcoding problem.... Anything else will play fine using bubble upnp and mxplayer with very little wait time; it's not instant but only 3-4 seconds usually.
I still have the same problem on 1.52.1 and have noticed that media is rendered as mpeg2/ac3 which does not work. 1.51.0-sb58 served media as mpeg4/mp3. I have appended debug log for both 1.52.1 and 1.51.0-SB58. Many thanks.