Have you updated the iPhone recently ?.

My Garmin 1000, which initially required multiple attempts at pairing to my iPhone for the BT BLE connection, but once setup, worked fine for 2 years, no longer automatically connects on the basic BT. I have to now do a manual connect and this is after the latest iOS update. I think Apple changes stuff to **** with people and Garmin sure ain’t the best company to keep up with this stuff.