I have a feeling I know the answer to this, but would like to toss it out to others, including the experts in here. This morning, I actually connected, and sync'd my Fenix 5+, and all was well. I noticed I wasn't receiving any notifications, and the watch said "BT Offline". That's okay, happens, right? So, I go in, and turn BT off on the phone, wait until it reconnects to the fenix, and go into Garmin connect, and try to sync. Nope. I turn the watch off, turn the phone off, turn the phone back on, then the watch, watch the fenix "connect" in the Bluetooth settings on the phone, go back into Garmin Connect, and nope, still not connected. I do the "12 second light press", and nope, nada. Okay, well, I've been using the 6.64 beta, that includes the BT update, so I reinstall that. Restart, (using Android File Transfer, I'm on a MacBook Pro), the watch updates, still BT Offline. I remove the watch from the phone, hoping it will re-connect, and here's the sad part. When I restarted the phone, the Watch does not present itself for pairing. I try to force pairing per the manual (Light Press, the little icon with the phone and BT symbol), and all it says is "waiting for phone". I suspect my BT chip/whatever on the watch is tits up, what do you think? (Oh, and I can't get MapUpdater to discover the watch, even though Garmin Express, and Android File Transfer find it just fine with the cable.) I was thinking of reinstalling the entire firmware.
Never mind. Did a reset on the phone, and the BT came back. Noticed this when I was trying to sync my Apple Watch, and the activities app just showed a blank screen. Therefore, problem was with phone, not watch. Now, Why did the stupid phone decide to make the BT go bye-bye? Anyway, all is better.