Hi @hanhey you won't lose anything, your data is safe in the cloud under Fitbit.
May I ask what phone you are asking about?
Have you tried stopping the Fitbit app?
Best AnswerThis has happened to my Fitbit app on occasion. It happens to other apps, too. I have an iPhone SE. The solution for me was to force close all open apps (double press Home then swipe up on all open apps). This usually does the trick. If it does not, I turn the iPhone off (Settings > General > Shutdown) ... give it a few minutes ... then turn it back on. This has resolved my problem 100% of the time.
Another thought - Sometimes it seems to be an overload issue on my iPhone. Check is to see how many screens are open in Safari. Too many open screens can really slow things down and interfere with overall performance in other apps. I know this because my hubby never seems to close them. I’ve actually gone in and closed over 48 screens at one time!
None of those things worked (did all that before I posted). Support suggested I log out and log back in again. That did the trick although the reset made it say I burned 6000 calories yesterday for some reason LOL. But everything seems back to normal today.
Best Answer