I filed this as FB11451378. In the mean time I'd appreciate any pointers on how to get this working. Some potential workarounds I'm considering are using an older API for screen capture, or make a small helper XPC service in native macOS code that'd do the capturing, but it'll probably be more complex than it needs to be.

I was about to post a similar question, since I've been struggling with this exact issue for the last 3 days. The default app clip does not pop up when invoked from a QR code or NFC with a URL of the associated domain. I've read and re-read the docs (and re-watched all the app clip WWDC sessions) and they never directly address this. I'm suspecting that yes, Advanced App Clip Experiences are needed to use associated domains. The docs say: A default App Clip experience is required and can be invoked using Safari and Messages, as well as through an NFC tag, QR code, and links in other apps when using an Apple-provided App Clip link. Incredibly confusing. Why do Safari and Messages support the associated domain and not NFC or QR? And why not just say that in simple terms? I'd love for someone from Apple to confirm what the expected behavior is.

Were you able to solve this? I’m having the same issue where my Advanced app clip experience has been in status Received for many days. I’ve been in touch with developer support but doesn’t seem like anyone who answers my emails knows much about app clips.