After a lot of back and forth with support trying to explain the issue they have managed to replicate it. This is a bug and has been reported to the devs.
Did you find a solution to this? I got the same issue. Sure you could use the id to get the src but I’m using WP headless and therefore needs the url / object returned through the API, which it doesn’t.
Is there a solution to this? I’ve just now encountered the exact same issue. Reluctant to build my own block for this but I guess I have no choice.