just to add, from what i understand from your original post, your selection rules should look like this:
For the office staffs who work from mon to fri and no work on sat, sun and Public holiday.
( 1 1111111)( 1 1111111)( 1 1111111)
For the retail store who work from mon-sun with off day on Thursday and they are required to work on PH.
( )( )( ) --> all blank
Kindly check if this is working for you.
Public Holiday Class for the Holidays defined for your office staff should have value 1. For Retail staff who are supposed to work on PH, the Public Holiday Class should be blank in definition.