Shift details issue in Absence Duration FF on specific work schedule patterns?

Summary:

I'm using a Absence Duration FF on all the Absence Types and it's normally working correctly. It uses details from the Assigned Shift or the Published shift. However, I've noticed a strange behavior only when the employee is assigned to a Work Schedule with a Workday Pattern with length greater than 28 days. Does anyone know if there's anything wrong or does anyone had this issue?

Content (required):

Hello!

We have a Absence Duration FF to calculate the duration taking into account some shift details. This is normally working fine for all the employees. This formula uses the details from either the Assigned Schedule or the Published Schedule. To handle this situation, I check if this exists.