My wife and I both have the same problem. It all started when we installed the latest update. I am getting very frustrated, after looking at all 10 pages of Samung users getting no help from the big corporation.
Today i got an system update to my samsung A8. After update everything is working like it should. Fitbit Notifications is working (calls, messages and calendar), syncing works, excersice loggin with gps and no pairing errors ( charge 2 is is not visible at bluetooth menu). It seems that problems are now fixed at last!
It seems that there was something wrong on
Android 9 or/and Samsung itself and not in fitbit app ( in my case). But still this has been worst customer experience i ever had. Zero points for Fitbit and Samsung because both is telling same bull***** again and again even they know the reason for sure.