I just logged FB7793239 with the same issue as OP. I've attached as much as I could to the report, including the two commands you asked for.
mpdifran
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I think you need the client_id in this body as well, so something like this:
{
		"client_id":"com.domain.app", // App Bundle ID or Service ID
		"grant_type":"authorization_code",
		"code":"test",
		"redirect_uri":"https://example.com",
		"client_secret":"eyHrt*****"
}
More info can be found here - https://developer.apple.com/documentation/sign_in_with_apple/generate_and_validate_tokens.
I've built an app to help make screenshots for the App Store, and it has support for Apple Vision Pro as well. Once you've created the screenshots, it's super simple to localize them, and you can then upload directly to the App Store!
https://picassoapp.ca
Yup still experiencing the same issue with RC1. Anyone have a workaround?
I too am hitting this problem, and it is very frustrating. Removing the support for app groups and shipping a new version should be sufficient.