If you have been into the absence section of a staff profile and added an absence period which then doesn't display on the front page of the profile, have a look in admin>personnel>manage staff attendance and see if there are any present codes for that staff member in the date range. If there are then remove them by ticking only the box for that staff member, filling in the maths sum at the bottom of the screen and then clicking the Remove codes from [date range] button.
This should allow the absence to display on the staff profile.