ok ... thanks to link from MarcGuay managed to create two playlists 1 called dynamic.m3u (10, 000 tracks) and another called root.m3u (13,312 tracks) I realised that the default settings were max 10,000 tracks for a playlist so I went into settings and raised it to 15,000 before creating 2nd playlist called root. So now I can play the tracks in a random order using the root.m3u playlist and the crossfade on mix is working a treat.
Can someone advise how to delete a playlist I don't need the dynamic version that was limited to 10,000 tracks. TIA