Logically this is because the project is considered inactive and all of it’s actions are ignored.
But I think the focus should work regardless.
Edit:
I misread your report. It works as designed.
As I said above, what you expect makes sense logically, but the point of Focus is to always remain visible regardless of the item/project status.
I am also bothered by the way schedule + focus works. I can’t focus on my focus tasks if it is clutter with things that don’t have immediate value
I think scheduled items in the future should never show up in any view by default because they can not be acted on before a specific date. This is somewhat linked to this comment about OmniFocus, a scheduled task should not be considered an available task.
The way I use focus + schedule is for task that I know already that the moment they are workable they should be my focus.
OK that I did not know, the doc don’t cover the schedule part so I did not expect it to auto-focus when the date arrived!
Then all is good, sorry for the noise