I don’t think Fly would in anyway gate such a thing behind plans, given how much Kurt dislikes companies that do so, like Cloudflare (?).
Btw, this means you’re entitled to email support with guaranteed SLAs (?); and do let us know what the issue really is, if they figure it out.
You may have probably tried this, but fly status --all -a <app-name> & fly ips private & fly info -a <app-name> might show some helpful additional information.
I believe something in the release_command might be getting in the way. Is there a way to remove or avoid running it for a test deploy?