Sidecar Not Working (M1 MacBook Pro => M4 iPad Pro)

MacBook Pro M1 16"

iPad Pro M4 13"

At the moment I'm able to use screen mirroring from iPad to MacBook, but not the other way around (which is my intended use-case).

I've stumbled upon at least 20 similar questions, and non of the proposed solutions worked for me.

1. Honored all sidecar requirements Use an iPad as a second display for a Mac - Apple Support
2. Tried a bunch of troubleshooting steps https://www.lifewire.com/fix-sidecar-not-working-on-ipad-5224486
3. 2FA enabled; Handoff enabled; Both on same wifi (and also via USB)
4. Tried resetting both networks...
5. Both are on the latest update (Mac 15.1, iPad 18.1)

In the end, I actually completely reset both devices, and it's still not working.

But when I try to use my older iPad (4th gen 11"), there it works as expected.

So for whatever reason, my M1 => M4 setup doesn't work. Any ideas would be appreciated. 🚀