Syncing difficulties with Samsung Galaxy S5

[itsis]

My fitbit charge 2 has been syncing fine until 13.20 yesterday.  I usually use a Samsung S5 but as of yesterday I can't sync it with any device though it is registering readings.  Any help out there?? I badly need it for health condition.

Moderator edit: Subject for clarity

[RicardoFitbit]

Hello @itsis, welcome to the Community Forums! It's a pleasure to assist you today.

Thanks for bringing this to my attention. If you haven't already done so, I recommend you to check how the syncing procedure works here and see if there's a missing requirement on your Android mobile device that's preventing the syncing procedure to be completed. Also, you can move forward to the troubleshooting steps that are specified on: Why won't my Fitbit device sync? and let me know how it goes. 

Keep me posted, I'll be around if you need anything else.

[itsis]

Have to admit I'm confused...  I've spent hours trying to sort this. 
Yesterday I managed to sync it with Windows 10 which is too heavy for regular use and it then started syncing on the Samsung S5 but stopped again after 2 hours!
I have a chronic illness and need to keep track of my HR throughout the day.  This function doesn't seem available on Windows 10.
I got the S5 as it was compatible with FB charge 2 and has worked well for many months - until last Friday.  Am I expected to buy a new phone because FB have updated?

[itsis]

Now it won't connect with either ... though both say it is paired but unable to find device...
Is this a problem with the watch or FB??