Similar problem w Bose Mini Soundlink (wow) and S5:
They pair easily and usually work, but sometimes they connect, the Bose bleeps, the S5 mutes for a second, then carries on playing music from its internal speaker.
In the S5 BT settings, the Bose shows as connected and ticked for audio streaming.
Various problems w trying to do a Mini Soundlink FW update...
Temporarily solved by restarting S5...
I connect to my own and a friend's Bose Mini so rename them on the phone to distinguish. I sometimes wonder if the Androids or Boses are getting confused by the renaming or pairing to 2 almost identical speakers...