Getting version number of unreleased version

I am using the App Store Connect API, specifically the endpoint to get prerelease versions: https://api.appstoreconnect.apple.com/v1/apps/{id}/preReleaseVersions



The return results seem to be missing the 'next' unreleased version.


That is, if I create a new version for an app and I have not uploaded any builds for it yet, I cannot get the preReleaseVersions data for it.


I need to get the version number for the unreleased version via the API but it does not seem to be available at all. Is this a bug with the preReleaseVersions endpoint, or is there another one to hit to get that data?