Remove the Logitech Wireless Mouse USB Receiver that was plugged into
the USB-C to USB converter (I use this converter to connect both the
Wireless mouse AND my iPhone via USB to Lightning cable). This
REPRODUCABLY caused the described error "Failed
_shouldMakeReadyForDevelopment check even though device is not locked" to reappear when I repeated the re-pairing procedure with the
Logitech adaptor plugged in
Not successful:
Unpairing (from both Macbook or iOS - Settings - Developers - Unpair)