Can't seem to find any other articles about what I'm seeing. I just began using the iOS app on my 6s, also concurrent logging with my Garmin 510.
At ride end, I use the iOS app to save the ride, and post to Facebook. It also shows up in my log on the web based RWGPS. However when I look at the data, the Max speed is completely wrong, IE: 65+ MPH vs actual 24 MPS. Also the heart rate data isn't transferred.
Initially I thought it was an error with the APP, but if I look at the ride data on the APP, the speed is correct, and the heart rate is logged correctly. Not sure if that is coming from my Garmin.
So this looks like a problem with how the APP moves data to the web, then I assume any Facebook post takes its data from the web, not directly from the APP.
So far, I've just been deleting the ride, and using an upload from my Garmin.
Is there a setting I'm missing somewhere? iOS 9.0.2 (13A452) Windows 10