I am also struggling with maintaining a consistent bluetooth audio connection from the SDMX28 to my Bose SoundSport Free (SSF) earbuds. The bluetooth wireless pairs between the devices just fine, but half the time I cannot hear any audio to play. I can see the song running on the player, but there is no sound heard in the SSFs.
https://www.amazon.com/SanDisk-SDMX28-016G-G46K-Sport-Player-Black/dp/B01LW2F237