Epix (Gen 2) Pro 51mm, iPhone 15 Pro Max, Bluetooth connection extremely unreliable

I have both and no problems here whatsoever. Try soft resetting your phone or resetting network settings. 

You say re-paired, but did you delete it in iphone BT settings first. My experience is that iPhone bluetooth connections restored from another iPhones backup are not stable.

I’m the same, but not as often as you (yet) Same set up except with iPhone 15 Plus. Phone says it’s connected but Epix tells me to open the app when it is.

Very hit & miss.

I also face similar issues. The phone recognises that the Epix Pro is connected, but the app does not. This is intermittent. When it does connect, syncing does not carry all teh data from the watch to the app. Parts are missing (sleep data, body battery, stress level, and more). The connection to the app is then lost before synching is complete. 

I am not impressed with the behaviour of this flagship device. Is seems that Garmin has some work to do on bluetooth to make this more stable. In the meantime, much of the data I want to view is not visible in the app, and therefore not on the web interface either.

You can sync via WiFi or cable as workaround.

As I said above, if you have upgraded your phone and restored BT connections from backup, that doesn't work well. That is not limited to Garmin devices and I see it as an Apple problem.

Call garmin support perhaps?

Yes, I did delete the device from iOS Bluetooth list.

I'll try this. Thanks.

Syncing via WiFi or cable works, but I'm losing the "instant"/"continuous" sync experience. And the fact that I'm intermittently missing phone notifications during these BT disconnects makes it less of a smartwatch.

I'm glad to hear that at least there are people out there with the same setup that do not have this problem. Converging towards my specific iPhone network/BT situation.