Schedule a page missing from pages library

[NickMumby]

The schedule button is missing from my site pages library. 
Is there a feature that need to be enabled or this?

https://support.microsoft.com/en-au/office/schedule-a-sharepoint-page-or-news-post-to-go-live-at-a-s...

[#2]

Has anyone published a content type to the library? That can break the scheduling feature - see https://learn.microsoft.com/en-us/sharepoint/troubleshoot/sites/cant-schedule-publish