Hey @jasonknebel we were able to fix it using the new format.
Someone replied at Feedback Assistant to try the new format again and it finally worked!
We had to change these two arguments from 'EN' to '${EN}':
// Before
'data.relationships.localizations.data.0.id' => 'EN',
'included.0.id' => 'EN',
// Now
'data.relationships.localizations.data.0.id' => '${EN}',
'included.0.id' => '${EN}',
If that helps, do you mind sharing a URL of one of your app clips or just manually check this thing scanning an NFC card with a URL that uses your app clip host but random path that's not associated with an app clip? https://developer.apple.com/forums/thread/803187