Unmerge Cells and Fill with Duplicate Values

[Excel Fox]

Try this...

Sub FillEmptyRanges()
    
    Dim rng As Range
    Set rng = Range("A1").CurrentRegion.SpecialCells(xlCellTypeBlanks)
    With rng
        .UnMerge
        .FormulaR1C1 = "=R[-1]C"
        For Each rng In rng
            With rng
                .Value = .Value
            End With
        Next rng
    End With
    
End Sub