I have the same issue. I am running a Windows 10 pc, version 1809 64-bit Enterprise. The pc is dell Latitude 7370. The iPhone is a iPhone 8 with IOS 12.1 installed. I have tried multiple times to connect the iPhone to the pc via Bluetooth.
I have run the troubleshooter, enabled the Bluetooth Support Service to Automatic, updated the Bluetooth driver (Intel), and I have tried older versions of the driver as well. I have all the windows update patches installed. I have restarted my phone and pc too many times. I have removed the Bluetooth driver and deleted the driver to let Windows select the driver. Nothing works.
My iPhone will pair with the pc, but is unable to connect. Every time I try to connect, it tells me either the connection failed, or, my pc is not supported, and the only option I have on the iPhone is to 'Forget Device'.
From my searching, this is a prevalent issue with iPhone's and Windows 10. My other Bluetooth devices all connect without issue. I have ran across multiple steps to troubleshoot, none work.
Please verify if there is something I am missing?