Selecting iPad from the Airplay drop-down or in Sidecar utility in System Preferences causes
"Unable to Connect to iPad. A miscellaneous error occurred (-402)" to occur.
iPad Pro running iPadOS 13 beta build 17A5534f.
Macbook Pro 2018 running macOS Catalina 10.15 build 19A487m.
Have tried while connected to the Wifi network and also connected via USB C with Wifi turned off on iPad.