Detecting Hidden Rows

It should be noted that ListHiddenRowsCols (see my previous comment) must be used with newer versions of Excel (2021+) that support dynamic array functions. It doesn't work with My Excel Toolbox's SpillArray function in a cell formula; I don't know why yet. However, it could by called by a macro (Sub) with results in a MsgBox or posted to a worksheet.

In the VBA code of my previous comment for the simplified version of ListHiddenRowsCols, this statement
    With ActiveSheet
should be replaced by
    With Application.Caller.Worksheet
This assumes the function will be used as a UDF in a cell formula.

My Excel Toolbox includes the following function to return a list of hidden rows and columns as a dynamic array:
=ListHiddenRowsCols([AllSheets])
If AllSheets is FALSE (default), only the current worksheet will be evaluated; if TRUE, all worksheets in the workbook will be included.
This function considers the "used" range from cell A1 to the last non-blank cell or the last formatted blank cell (Ctrl+End). It normally returns hidden rows beyond the used range, but it returns hidden columns beyond the used range only if they were adjacent to the used range before they were hidden; such columns are added to the used range even if they are subsequently unhidden. The used range is reset when the workbook is closed and reopened.
Here is a simplified version of the function:

Public Function ListHiddenRowsCols() As String()
    Dim A() As String, B As String, C As Collection, n As Long
    Application.Volatile
    B = "[" & ActiveWorkbook.Name & "]"
    Set C = New Collection
    C.Add "Hidden Rows/Cols"
    With ActiveSheet
        ListHiddenRowsCols_Do B, .Rows, _
            (.UsedRange.Row + .UsedRange.Rows.Count), C
        ListHiddenRowsCols_Do B, .Columns, _
            (.UsedRange.Column + .UsedRange.Columns.Count), C
    End With
    If C.Count = 1 Then C.Add "None"
    ReDim A(1 To C.Count, 1 To 1)
    For n = 1 To C.Count
        A(n, 1) = C(n)
    Next n
    ListHiddenRowsCols = A
End Function

Private Sub ListHiddenRowsCols_Do(Book As String, _
    Obj As Object, Nbr As Long, ByRef C As Collection)
    Dim nBeg As Long, nEnd As Long, n As Long
    nBeg = 0
    For n = 1 To Nbr
        If Obj(n).Hidden Then
            If nBeg = 0 Then
                nBeg = n
                nEnd = n
            ElseIf n = nEnd + 1 Then
                nEnd = n
            End If
        ElseIf nBeg > 0 Then
            C.Add Replace(Application.Range(Obj(nBeg), _
                Obj(nEnd)).Address(External:=True), _
                Book, "", 1, 1)
            nBeg = 0
        End If
    Next n
End Sub

See https://sites.google.com/view/MyExcelToolbox/

I noticed that when you put the color in and you still have it selected with the ALT+; there are breaks in the color where the hidden rows are located. Very helpful for finding the hidden without un-hiding the rows.

I also adapted the code to do the same for hidden columns and then both columns and rows.

Nice lesson, Thanks