AppClip: Associated Domains -> Invalid Entitlement: Missing Section

Question

I'm trying to setup an appclip in my app. I've added the associated domains to both the main target and the appclip target

appclips:mysite.com

I've added to the AASA file

"appclips": {
   "apps": [
      "XXXXXXXXXX.com.mysite.mobile.develop.Clip",
      "XXXXXXXXXX.com.mysite.mobile.Clip"
   ]
}

When I go to AppStoreConnect > TestFlight > iOS Builds > Build# > Build Metadata > View Status

I see this:

Invalid Entitlement: Missing Section

When scrolling to the bottom of the Build Metadata I see the Entitlements section and this line is present in both my Main Target and AppClip target:

com.apple.developer.associated-domains: ( "appclips:mysite.com" )

I'm not sure what I'm missing. What does "Missing Section" mean?

I've followed the instructions on setting up the appclip but can't get past this. Scanning the QR code brings up the appclip using Local Experience.