I've had an F3 for a long time and just bought a 6X Sapphire, but for the last few days I've had real problems with it not auto reconnecting whenever the BT connection is lost between the watch (v 9.00 firmware) and my phone (Samsung) which uses the Garmin Connect app (latest version). Every time I walk out of range from the phone the watch face shows a pairing code, which fails, then it keeps attempting to repair until I cancel it all out. After literally half a day trying to wonder wtf is going on I realised (with help from another post in the 6X forum) that my Samsung tablet is causing the problem. If I turn the bluetooth off on that, the phone and watch function as expected. The tablet also has Garmin Connect installed but I haven't actually got round to adding the 6X as a bluetooth device in the tablet connection settings so I don't know how it's connecting up and causing this problem. The 6X shows in the devices list in the GC app but it isn't connected and as far as I am aware never has been ia the tablet.
I can't say I'm very happy with this really, OK I have a workaround but it means I now can't use my tablet if I'm away from the phone to watch or listen to any media using BT headphones as I have to turn the BT off or suffer the endless pairing attempts on the watch. I could do it but would have to have all three devices on me while doing so. I also use GC on the tablet a lot as it's easier to read than my phone. This seems like a bug to me, but was keen to hear what others think. Thanks.