Charge 3 not syncing with OnePlus 5

[Thespragg]

Right, I'm at my wits end with fitbit devices and need some help before I take this back and switch to a different company. 

I've had an Alta, a blaze and now a charge 3, all of which I eventually gave up trying to use the app with because they'd sync one day then go multiple days of not syncing no matter what I did.

I've tried to use them on an s6, s7 and now a Oneplus 5, and it's the same problem on all of them.

Is it really that hard to get a Bluetooth device to sync? My headphones have 0 issues, my car has 0 issues, so why is it that a company dedicated to making Bluetooth fitness trackers can't get their Bluetooth to work properly?

Before I get the usual "turn your phone off and on" reply, I have tried:

-turning phone off and on

-turning charge 3 off and on

-reinstalling the fitbit app

-removing my device and re-adding it to the app (it connected and set it up, then immediately failed to sync)

- resetting the charge 3 (same happened as above)

There doesn't seem to be any rhyme or reason to when it does decide to sync, it just happens every 3-4 days, and given how I've had this issue across multiple devices and phones I'm confident is not a manufacturing fault.

Also, I know the op5 isn't a supported device but these issues are the exact same as the issues I had on my previous phones which were both supported devices, which suggests that the fact my device isn't supported has nothing to do with the issues I have 

Moderator edit: Clarified subject

[LanuzaFitbit]

Welcome to the Forums @Thespragg.

Thank you for sharing all of those details on what you have tried to get your Charge 3 to sync to your phone.

As you mentioned, the phone is not supported and thus we can't guarantee that it will work with that particular phone. Having said that, let's try the following steps to see if that helps the Fitbit sync consistently:

1. Go to the phone's Bluetooth settings.
2. There, look for the Fitbit device (and all Fitbit devices).
3. Remove them from the list of paired devices.
4. Restart the phone.
5. Run the set up as if it was a replacement Fitbit.

That should help so that it starts syncing properly.

Please let me know how it goes or if you have any further questions.

[OnePlus5user]

Why aren't any of the new Android devices compatible? It's pretty annoying when your Fitbit works well with OnePlus One, but doesn't work with OnePlus 5 (which is almost a 2 year old device)