Sidecar

Mine will ONLY work with a USB C cable connected from my MacBook Pro to my iPad Pro.

Strange.

https://www.reddit.com/r/apple/comments/bx3eet/sidecar_support_on_older_macs/

I have a 2018 15" MBP running Catalina, and a 10.5" iPad Pro running iPadOS. I don't have a Sidecar pref pane in Catalina, but in Displays, I can go to AirPlay Display and select my iPad. And it uses my iPad Pro as a 2nd display w/ all the Sidecar features like the touch bar, etc.

Same issue 2015 MBP 13", with iPad Pro Gen3

I wouldn't over think it too much, Sidecar runs like a champ in my experience and the iPad Pro runs great with or without a cable hooked up. Apple did their homework very well building Sidecar. I can open Affinity Photo using Sidecar and use the Apple Pencil to edit photos like the application was built for pencil. I'd say even for a beta, its a pretty solid feature.

For older Macs ( mines a late 2012 MBP) paste this into terminal.....

defaults write com.apple.sidecar.display AllowAllDevices -bool true; defaults write com.apple.sidecar.display hasShownPref -bool true; open /System/Library/PreferencePanes/Sidecar.prefPane

you will then be able to use older Macs..

As of beta 2, I can run sidecar wirelessly on my iPad 6th gen. It is running pretty good despite the fact that I'm using a Macbook Pro 2014, which isn't technically supported.

I have a 2017 MBP catalina beta 2 and iPad Pro 12.9 in 3rd Gen, iPadOS beta 2. I get the option on my MBP in displays and in the settings menu but when I select it to connect to my iPad nothing happens. Plugged in and wireless has the same results.

Sidecar is still broken in Beta 5 for me on both iPad OS and macOS Catalina. Did someone get it to work?

Not workinfg on my 2018 MacBook Pro & iPad Air 2. It worked great with the first few macOS and iPadOS betas.

I have an iMac Pro and an iPad Pro both running the current betas. I don't even have the sidecar in system preferences on the iMac and the ipad doesn't show up in airplay when on wireless or when directly wired with USB-C.

EDIT: I got it to work. I had to select the iPad in Finder and establish the trust relationship. Now the iPad shows up in Airplay and I can extend my display to it. Sidecar also showed up in the System Preferences on the iMac now. It only works on the wired connection.

I have same issue by Macbook(late2017) with iPadAir2.
I couldn't find iPadAir2 from AirPlay.
Why?