When my Gear Fit is connects to my S5, why don't I have sound on either end when receiving or making calls?

[AC Question]

Gear Fit call issues through S4

When gear fit is connected to my s4 I have no sound on either end, when receiving or making calls through my S4. Call timer is going, but I can't hear them and they can't hear me. Turning off blutooth doesn't help, the only fix is to restart my phone. Swapped out sim card with t-mobile, and they swapped out my phone, thinking it was a phone issue. Once I removed the fit and the fit manager, problems stopped.
Phone SGH-M919
Android 4.4.4
T-mobile
Gear fit SM-R350
SW R350XXU0BNE5