Gods, yes, this. The FitBit app is like someone said "Let's use a wonderful asynchronous architecture so we won't block on retrieving data!" and then completely ignored all the ways that might lead to terrible UX if implemented poorly.

My steps stick at 0, then suddenly are the total of the last 3 days' worth. I log food, and it re-populates the "quantity" field with the old value after I edit it, sometimes up to 8-10 times in a row. My sleep data takes a roulette-spin amount of time to go get processed in the cloud and redownloaded, and even once the main dashboard has the info, the "Sleep" detail page will refuse to admit that I slept last night for another 3d20 minutes.

It's like someone connecting the pieces of a car with Slinkys instead of bolts because they're more flexible. If I didn't like the hardware so much I'd have switched ages ago.