I use my fr945 2.80 with multiple earphones, a pair of Anker soundbuds curve, Anker soundbuds spirit and jlab wireless sports 2.
All work fine once they're connected, however I've noticed that often I have to reboot my FR945 before a pair will initially connect. Starting music and selecting the the earphones won't automatically connect, Even though they're turned on.
Once I've rebooted it connects just fine and the connection stays strange through the entire workout.
I already tried a hard reset (holding the light button for 15 seconds) to no avail.