Conditional Formatting with overlapping ranges

Hi everyone,

I'm new to VBA programming, but with a lot of searching and studying code examples I have managed to make 3 working macros today. However I am stuck on the last one that I need to create. The aim is to have a macro that deletes and re-establishes our two conditional formatting rules on our sheet. The ranges overlap, and this seems to cause it the macro to stop working. If I run a version of the macro with either 1 rule at a time it works fine. If I run the whole thing with both rules, it gives a runtime error 438 and debug highlights the line ending xlDuplicate.

Sub ConditionalFormatting()
'
' ConditionalFormatting Macro
' Repair Conditional formatting
'
' Keyboard Shortcut: Ctrl+t


'Reinstate correct condtional formatting

    With Sheets("TnT")
       
       With .Range("B178:L10177")
             .FormatConditions.Delete
            .FormatConditions.Add xlExpression, Formula1:="=$K178:$K10177<=$F$2+7"
            .FormatConditions(1).Interior.Color = RGB(230, 184, 183)
      End With
      
        With .Range("B178:B10177")
            
            .FormatConditions.AddUniqueValues
    .FormatConditions(Selection.FormatConditions.Count).SetFirstPriority
            .FormatConditions(1).DupeUnique = xlDuplicate
            .FormatConditions(1).Interior.ColorIndex = 46
            .FormatConditions(1).Font.ColorIndex = 3
            .FormatConditions(1).StopIfTrue = False
        End With
        

    End With


End Sub

What changes can I implement to get this to work?

Also, I was hoping someone could please explain to me how this line of code works?

    .FormatConditions(Selection.FormatConditions.Count).SetFirstPriority

Thank you in advance!!