Just solved my incompatibility error message on garmin 1030 plus. I had to do 3 things -
remove my phone from the bluetooth list on the garmin device
remove my phone from the bluetooth list on the iphone
And (this is the bit I had not done) remove the garmin device from the connect app.
turn both the phone and garmin off and on
reconnect in the normal way
one more tip, when connecting your phone to the garmin 1030, it seems to work better if you accept to pair on the garmin and then the phone rather than the other way around.
Hope that helps