I was having the same issue. For me, what worked was opening Devices and Simulators (command shift 2 or Window -> Devices and Simulators) and disconnecting and reconnecting my iPhone with the window open. I then waited for the yellow banner saying the phone was being set up to go away. After that, the issue seemed to be resolved.
It shouldn't make any difference, but for reference, I'm on MacOS Big Sur, my iPhone is a XR, they're each running Beta 4 for XCode and iOS 14 respectively.