Some courses are not saved

Hello,

I recently noticed that some of my courses were not being backed up, even though they had recently been modified.

The backupreport says "queued":

And the log for \core\task\automated_backup_task says "not scheduled for a backup before ..." except that the backup never happens.

The settings for automatic backups are as follows:

I've changed the "Maximum number of backups kept" setting from "10" to "All" to see if that solves the problem, but it doesn't have any effect.

Manual backup works fine on the same courses.

If anyone has any ideas