I have the VivoActive 4, connected to my Jabra Active Elite 65t headphones and it plays music GREAT. No connectivity issues.
As soon as I tried to track and activity it disconnects my headphones and it is an endless cycle of connect and disconnect in my ears. I almost lost my mind after half an hour.
I found the solution here: on the FR945 forum and IT SOLVED the problem. I'm sharing it here to help anyone searching or experiencing this problem.