Brian, do you use forward incremental mode? In this case, indeed, the actual number of restore points on disk may vary from day to day
, depending on the full backup schedule. However with daily backups and weekly fulls 50 restore points is a bit higher than expected maximum for retention set to 21 (probably this is due to the recent changes you've made and excessive restore points will finally be deleted according to the new retention setting). What backup files do you currently have in the backup folder?