sidecar not working wirelessly

MBP 15", 2018 model

iPad Pro 2018 model


works via USB, does not work wirelessly, iPad is just not found.


Same WiFi, same AppleID, BT enabled, handoff works just fine


macOS 10.15.3 (19D49f)

iOS 13.3.1 (17D5026c)


But this has been going on for a while, so not specific to these software releases...


Clues anyone?