Google Sheets – Fix Formula Issues in Conditional Formatting

So, I have a Gantt chart style diary. I want to apply conditional formatting to any column whose date (in row 2), is a public holiday. There is a sheet called 'Public Holidays', that has the dates of all public holidays in column A.

I found a relevant formula to try from Peter Smulders answer to this topic: How to check if value is in range of cells?

Here's my version:

=NOT(ISERROR(MATCH(B$2:RV$2, 'Public Holidays'!$A:$A,0)))

Nothing happens. It doesn't activate on any cells or columns whether public holidays or not. Weirdly though, if I paste that formula into a bunch of cells, it returns correctly, ie any cell in a column whose date in row 2 is a public holiday returns TRUE and any cell in a column whose date is not a public holiday returns FALSE.

I don't understand why it works as a cell formula but not as a conditional formatting formula.

Any help would be greatly appreciated.

Here's a copy of my sheet: https://docs.google.com/spreadsheets/d/1sYI2oDyDR5p5oIJvE_AKIUm_PMReL4nGfXlMU5YvRxI/edit?usp=sharing