Switching your power meters (Quarq in my case) to use ANT+ will fix the calibration prompt issue.
To do this, first check your power meter and verify it's using BLE. If it's not, then this may be a different issue for you. You can see this in the 'Show Details' section of the power meter. If it's BLE, disable the power sensor (don't REMOVE it). Then do 'Add Sensor' and add the same power meter. It should choose ANT+ this time, possibly with a different name. Verify it's ANT+ like I mentioned above. You can then REMOVE the BLE version of the connected sensor.
I think Garmin will be making the default ANT+ in an upcoming code update until they get this BLE issue resolved.