Ionic not syncing

[fitbyt]

When I open the fitbit app 1 of two things happen.

a) it starts trying to sync my Ionic, but then crashes

b) it doesn't try syncing but instead is 'looking' for the Ionic.

Firmware is updated, up is up to date. Started happening a few days ago. I've restarted app and Ionic multiple times, forgot bluetooth device and reconnected twice. When connecting the "new" Ionic i get trough the phase where a number is displayed on the watch, and then entered into the app. I see a green checkmark on the device, and then immediately the phone app crashes.

help?

Moderator edit: Updated subject for clarity

[SilviaFitbit]

@fitbyt A warm welcome to the Community. Thanks for the details mentioned and the troubleshooting tried. 

It seems like you tried to set up your Ionic once again and that's why it's asking you to enter the number. In this case, I would like you to confirm you've tried this syncing troubleshooting. If you did but your Ionic is still not syncing, please let me know the phone you're using. 

Keep me posted! 

[fitbyt]

yeah, that was not it. it did suddenly sync yesterday, but today it seems
to not be able to find the device again. at least the app hasn't crashed
yet today

[SilviaFitbit]

@fitbyt Thanks for getting back. I would like you to let me know the phone that you're using. Could you confirm that you followed the troubleshooting posted above? 

Keep me posted.