This may be the result of human error, where meals have been deleted accidentally by a member of staff at your school. To check, please head over to Admin > Meals > Manage Student Lunches:
Select the date you believe the meals are missing from, and which year group and/or Form it applies to (or leave as "All"), then click Choose.
Look down the list to see if there are any greyed-out ticks against certain meal types (meaning the meal previously selected has been deleted). When you find one, you can hover your mouse pointer over the tick, and a floating box will display telling you the date and time the meal was deleted:
Check with any relevant administrators/teachers to see if there is a valid reason for the deleted meal (e.g. a school trip). Once you have confirmed it was an error, you can reinstate the meal to the record by clicking the grey tick, turning it back to green. The Kitchen List report will now show the meals for this year group as intended.