iOS 13.6.1

Did you reboot both Mac and device ?

I too am having this issue. I have rebooted the device as well as my machine.

Xcode version: 11.7 (11E801a)
OS: 10.15.4 (19E266) Catalina

Here is the error displayed in the Devices window:

Code Block 
The current device configuration is unsupported. This iPhone X (Model A1865, A1901, A1902,…
To run on this device, please update to a version of Xcode that supports iOS 13.6.1. You can download Xcode from the Mac App Store or the Apple Developer website.

In the Issue Details:

Code Block 
Details
The current device configuration is unsupported. This iPhone X (Model A1865, A1901, A1902, A1903) is running iOS 13.6.1 (17G80), which is not supported by Xcode 11.7.
Domain: com.apple.dtdevicekit
Code: 601
Recovery Suggestion: To run on this device, please update to a version of Xcode that supports iOS 13.6.1. You can download Xcode from the Mac App Store or the Apple Developer website.
User Info: {
  DVTRadarComponentKey = 487927;
  DeviceType = "iPhone10,3";
}
--
Unable to locate ideal DDI for platform: <DVTPlatform:0x7feface39c20:'com.apple.platform.iphoneos':<DVTFilePath:0x7feface39ba0:'/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform'>>, version: 13.6.1, build: 17G80
Domain: com.apple.dt.DVTDeviceSupportFilesError
Code: 2
User Info: {
  DVTRadarComponentKey = 487927;
}
--
System Information
macOS Version 10.15.4 (Build 19E266)
Xcode 11.7 (16142)

I tested on MPB with MacOS 10.15.6 and Xcode 11.6.
I could compile and load to an iPhone X with iOS 13.6.1
I did it for 3 apps, including one with WatchOS companion app.

I then updated iPhone to 13.7 and app continued to work.

Note: I had to reboot both MacBookPro and iPhone to get it work.

I fixed the issue.

I needed to update my device to 13.7. Don't know why but that resolved it.

Same issue for me. Tried to reboot device, Mac, change cable and no luck. Upgrade to 13.7 fixed issue. Strange that latest Xcode doesn't support one of earlier version of iOS.

Apple, is that a way of forcing me to upgrade my iOS from 13.6 to 13.7?