Syncing activities from 830 to GC via iPhone

This is exactly my experience too with iPhone. It will only connect if the GC app is first opened, and will only upload after a ride if the GC app is left running in the background. If it's closed and the 830 is put to sleep, once reawakened it will not connect until the app is again opened.

But where is this stated, either in the Edge 830 manual or the GC app info?  Nowhere that I can find. For example: 

https://support.garmin.com/en-GB/?faq=9BcXLSQ4A22gasLarkUvH6&productID=125677&tab=topics&topicTag=region_bluetoothconnectivit

I would have thought that this page would have been the perfect place to add an instruction to always keep the app running in the background, if that was the intended behaviour. Or why doesn't the app warn you when closing it that sync will stop working?

Meanwhile, other bluetooth devices manage to reconnect to iPhone without needing specific apps running, so this creates obvious confusion in user expectations.

On my 520 it connects to my phone automatically when the phone is within BT range, without me having to unlock my phone.  On the 830 I have to unlock my phone, bring up the GC app. from the background to the foreground, before the 830 will connect to the phone.  If I don't unlock the phone the 830 will say 'searching' on the status screen but never connects to the phone.  So I cannot agree with you that on the 830 it's by design the BT connection is only possible with the GC opened in the foreground.

I should mention that I don't carry my phone with me on my rides.  I wear an Apple Watch.  So I finish my ride when the phone is within BT range.  On the 520 the BT connection works like a charm without me touching the phone upon the finish of my rides.

I'm still having the same issue however I just checked my iPhone and noticed GC 4.19.1 is now available.  I just downloaded it and will see if my problem persists tomorrow after the ride.

It’s never worked that way with my 510. The 510 just connects and works without having to touch the phone. It’s been that way across numerous iPhones and Galaxy S7 and S9.

With GC 4.19.1.1 my BLE connection problem persisted.  I manually opened the GC app. and my 830 connected but the ride upload failed as I got the dreaded 'upload failed' message.  I was busy trying to get the ride uploaded while my riding buddy who has the Wahoo Bolt finished packing his bike in the car.  I was so embarrassed.  After much trial and error the ride finally got uploaded.

I have GC 4.20 for iPhone.  My Edge 830 is at 3.50.  Itwas connecting fine to at the end of a ride to upload the saved ride until about a week ago.  Now it doesn't upload until I get to wifi.  Is this a new issue?

With the latest beta firmware, it still doesn't want to upload the ride via BT.  Not automatically after a save and not manually.  Once I get near my WIFI connection it loads automatically.  I expect to do some touring where I won't be around WIFI and this is one of the reasons I purchased the 830 to replace my 800.