Solution : I had the same issue , can't make calls with the buds in whatsup. The Fix is :
1- open galaxy wearable app
2- go to notifications
3- click on manage notifications
4- scroll down , choose the app and allow notifications
Have you tried resetting the buds through the Galaxy Wearables Application?
I just buy the galaxy buds and the mic doesn't work in other applications (whatsapp or Duo) apart of phone calls. I tried to reset them, update the firmware and give permissions but still not working. If had known this I had never bought them.
What type of device are you pairing with your galaxy buds?