You and apparently everybody else! I'm waiting for some kind of quality statement from Fitbit on this issue, as at the moment they are remaining tight-lipped.
It appears to be the GPS signal / lock on your phone that is weakening, which causes this condition. I dont think it is actually a Bluetooth related disconnect.
Without fully understanding what is going on it is difficult to offer any advice, other than to say you are not alone. I use a Google (LG) Nexus 5x, and I too am suffering this, every single time I run with the Blaze. I track the run in another app on the phone at the same time, and this is perfect, so even if the GPS signal is weak for a moment (enough to upset the Blaze) it is fine for the other app on my phone which tracks the run perfectly.
I think a software fix is required, I have tried all sorts and cant find a way to work-around this. All I can suggest is that your phone is in the best possible place it can be for GPS signal, and perhaps you try WiFi off, and avoid bluetooth headphones, on the off chance that this causes extra interference that could contribute, but in honestly, nothing seems to really make any difference.
As I say, still patiently waiting for an official statement from Fitbit on this. I think its very poor that they arent acknowledging this as a "known issue" as there are plenty of people suffering it.
as a workaround, try tracking your run in the Fitibt app, as that will log the activity accurately, regardless of whether the Blaze disconnects or not. However, you will end up with two activities, so you may want to delete one of them. Ideally keep the activity tracked from the Blaze, assuming it doesn't disconnect, as this will have the heartbeat data on it. Otherwise, they will be very similar.
Make sure you formally log this with Fitbit support, as they need to be issuing a support bulletin about this !
No longer a fitbit device user
