Connection issues with Edge 520 Plus

I could not pair new out of box 520 plus to iPhone 8+ with latest GC app. I had to install Garmin Express on my laptop and upgrade firmware on 520 plus, then pairing was possible.
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Same issues here, does it stayed paired after switching off then back on again? I can get my iPhone to pair as a first time pairing, but have to go through the whole pairing process every time I turn it on.

I'm also having problems with my iPhone SE. Bluetooth connection never worked out of the box so I did a full reset of the 520 Plus, removed Garmin Connect, etc, etc. I set it up again via Garmin Connect and the phone picks up the device and completes the installation process. If I then check the iPhone Bluetooth settings, Edge 520 Plus shows as Connected but BT_Edge 520 Plus is Not Connected. I can tap on BT_Edge 520 Plus and it momentarily shows Connected but immediately goes back to being Not Connected.

Not sure where to go from here and I've given up trying to make it work. I've accepted the increased battery life and better mapping were worth the upgrade from my previous Edge 520.

Maybe a future firmware will fix it?

Same issues here, does it stayed paired after switching off then back on again? I can get my iPhone to pair as a first time pairing, but have to go through the whole pairing process every time I turn it on.

That sucks ! Luckily mine does stayed paired.

Now my 520+ won't connect to my iPhone 8+
I looked at the iPhone BT settings and there were two instances of the 520+. I picked "forget this device" for both and they do not come back.
Not sure what to do.
This 520+ is the only BT device I've ever had issues with. Garmin does a really poor job with BT.

Pretty disappointed in the unit overall. The navigation is horrible and almost got me lost on a trail system today. Choose return to start using most direct route and the directions were not even close.

We're back to square 1.
Huawei P10, Garmin 520+, both on latest SW.
I'm able to pair garmin with my phone and syn'c it, but once I turn off garmin and turn it back on, no more connection.
Need to delete phone connection on garmin and garmin on phone and pair again to sync my ride. And so for each time I want to sync through my phone.

I had the same problem with my iPhone (and all other iPhones in my house, 4 in total), no more connection after turning Edge 520+ off. I had to delete phone connection and pair again to sync. I got a replacement unit. Now I "only" have to start Garmin connect on my phone twice to establish a connection. If I re-pair the units the connection actually works by only turning on the Edge for a whole day. A great improvement... The saddest thing is that Strava live segments doesn't work on the new unit whereas it worked on the old unit. The quality isn't the best.

I have both forerunner 920XT and edge 520 plus. I must remove device every time I try to download an activity. For the forerunner 920XT, it is easy and takes less than a minute (delete device and put it back).
For the 520 XT, here is what I do (iPone 8+):
1- forget the two bluetooth connections (BT_Edge 520 Plus and Edge 520 Plus)
2- delete the 520 plus from garmin connect on phone
3- On garmin 520, go to settings-->phone-->forget your phone
4- Go to garmin connect on your phone and reconnect your garmin edge
5- Sync

For the Edge, it is a freaking pain in the butt and takes about 4/5 minutes but it does work.

I am still frustrated by this issue with my 520 plus and my Note 8. I gave my wife my original 520 and upgraded myself to the 520 plus. Looking more and more like she got the sweet end of this deal. It would be pretty reasonable if someone from Garmin were to actually communicate in detail what is being done, or has been done, rather than offering apologies. Being completely transparent here, I prefer functionality over apologies. All I expect is for the device to work as intended. I should not have to delete/reconnect every time I want to have my 520+ connect to my phone.

Me and a buddy are both having this loss of sync issue with our 520+s... For both of us, the phone and 520+ both show connected, but syncing doesn't do anything. We have to remove the device and add it back to get it to sync by following the steps that Etienne2019 outlined above. But that only seems to work until the 520+ is powered off. I'm running the 4.01 Beta and have a LG G6 phone that is also paired with a Fenix 5+.. My friend is running the 4.0 FW and has an iPhone that is also paired with a 920XT.

Update: And now it is suddenly syncing without issue. Perhaps the recent update to Garmin Connect Mobile corrected this.