Please do not do a factory reset on your phone or fitbit or any other BLE device to try and make it work. We've done it plenty of times, it doesn't help. The problem isn't caused by any app or setting on the phone but instead by the firmware running the bluetooth LE code on the phone. The startup sequence does not complete due to a bug on the phone firmware. There are workarounds you can implement on th 3rd party BLE device code (eg. fitbit), but they shouldn't be necessary so ultimately samsung needs to fix this. I've heard from a little bird that Samsung has found and fixed the issue but the update will take some time to get approved and released. This is 3rd hand knowledge though so who knows if that's true. Keep pressuring Samsung though to get this pushed ASAP.
Thanks for this very helpful information. I'm going to post a link to it in the Fitbit forums, where some people continue to demand that Fitbit fix this, and swear they'll buy some other device.