The main thing that causes staff absences to not save in the staff profile, is them already having a code in Manage Staff Attendance.
Go to Admin > Personnel > Manage Staff Attendance.
Choose the date of absence you are trying to enter and click "View Register"
You will be able to see if there is any codes already saved in this date.
Simply click on the code, and choose "Remove" from the dropdown.
Once the code is removed and the date is back to showing red boxes. Go to the profile and re-enter the absence.
Please note the information in Manage Staff Attendance WILL pull through to reports, it just will not show on the staff profile. This guidance is for if you need the absence to show on the staff profile.