Blueprint - Multiple device selector isn't working

[crimson belfry]

I'm trying to use a device selecto in order to send a notification to multiple devices.
The issue is that if I set multiple: true the dropdown is not shown.

I tried to search here but I just found something from a couple of years ago never really replied or solved afaict

I was going to open a github issue, but it looks so strange to me that no one ever faced it

Am I doing something wrong ?

    notify_device:
      name: Device to notify
      description: Device that will receive the notification.
      selector:
        device:
            multiple: true
            filter:
                integration: mobile_app

when multiple is set to true I get this error in console`