I just updated my MacBook Pro (2018, 15") to macOS Catalina (10.15), and my 11" iPad Pro to iPadOS (13.1.2).
Since then, I haven't been able to connect the iPad to the Mac in the Finder over Wi-Fi, although my iPhone works fine. (This means that iOS devices are shown in the Sidebar.) The Mac and the iPad are both connected to the same network, too.
So, for instance, I can't sync the iPad in Music and Sidecar doesn't work as the iPad just doesn't show up in the window. Both of these things work over USB.
Does anybody have insight as to what might be going on? Thanks!