Actionable Notifications on iPhone not working

I am trying since an hour to get actionable notifications working on my iPhone.

I followed the guide: Actionable Notifications | Home Assistant Companion Docs and also tried a notification blueprint.

This is a sample script I tried

service: notify.mobile_app_iphone_12
  message: this is a message
      - action: MY_CUSTOM_ACTION
        title: Press me!

The notifications are being delivered but not as actionable notifications i.e. there is no button to press but just an ordinary notification.

All settings in the HA iOS app and the iOS settings appear ok. I am running the latest iOS and also latest HA app. Also tried to trouble shoot this with chatGPT but nothing worked.

Has anyone an idea what I am doing wrong?