QBO- An employee wasn't paid for a company holiday even though they have holiday pay set up. How do I prevent this in the future?

In QuickBooks Online Payroll, holiday pay for hourly employees is not automatically calculated, even if it is set up, Asher.

Holiday pay should be manually added to the timesheet or payroll. To ensure the employee is paid, open the payroll entry or timesheet for the pay period with the holiday and enter the holiday hours under the Holiday Pay category.

Here's what it looks like:
 

If you're using QuickBooks Time for tracking, you should first approve the holiday pay hours. Once approved, the hours will automatically populate under the Holiday Pay column. Please see the pictures below for visual reference:

If you underpaid an employee and haven’t paid them yet, you can create a new paycheck for the amount owed or add it to their next regular paycheck.

Please don't hesitate to revisit this thread if you need further assistance.