FWIW on both my iPhone 7 and MacBook Pro, I’ve had zero issues with Bluetooth no matter the settings.
With ANT+ there have been issues with dropped signals from time to time. For example, Nate was kind enough to look at one of my support requests and said there were 63 dropouts from my Stages power meter when connected by ANT+:
While it wasn’t a real problem, my solution was to stop using ANT+ and switch to Bluetooth.
If you go to DCRainmaker’s review on Edge 520, or Garmin forum, you’ll find a lot of people have ANT+ connectivity issues with Stages power meter.
@justinm given all of that, I suspect your real problem is using ANT+ and your Stages is broadcasting a weak or flakey signal on ANT+