Issues with a VBA For Next loop not working - excel

Question

I am trying to wrap my head around a piece of code that has worked for me in the past not working right now in a different application. Basically it needs to delete all rows that contain information in a specific column and leave the rest untouched. When I run the macro the code executes without issues, but just deletes some of the rows with values, not all of them. When running the code several times in a row it ends up doing what it is intended, but it's really not convenient. Here is the code:
Sub Delete_Signoffed()
Dim rCell As Range
Dim iCol As Integer
Dim iRow As Integer
Worksheets("MilestoneDueDate").Activate
If ActiveSheet.AutoFilterMode Then Cells.AutoFilter
ActiveWindow.FreezePanes = False
Columns.EntireColumn.Hidden = False
If WorksheetFunction.CountA(Columns("A")) = 0 Then
Columns("A").Delete
Rows("1:6").Delete
End If
iCol = Cells.Find("Sign-Off By", LookAt:=xlWhole).Column
For iRow = 2 To Cells(Rows.Count, iCol).End(xlUp).Row
Cells(iRow, iCol).Select
If Not IsEmpty(Cells(iRow, iCol).Value) Then Rows(iRow).EntireRow.Delete
Next iRow
End Sub
The source file has some formatting issues, everything that comes before assigning iCol the column value is to fix the format, so please ignore. iRow starts at 2 to avoid deleting the file headers.
Any ideas on why the For loop is not working as intended?
Thanks in advance!

Answer 1

I updated your script. I also added comments for you to be able to understand it better and able to improve it in the future.
Sub Delete_Signoffed()
'Goto CleanUp if there are errors
On Error GoTo CleanUp
Dim wsMilestoneDueDate As Worksheet
Dim rCell As Range
Dim iCol As Integer
Dim iRow As Integer
Set wsMilestoneDueDate = ActiveWorkbook.Worksheets("MilestoneDueDate")
'Disable temporarily Screen Updating
Application.ScreenUpdating = False
With wsMilestoneDueDate
.Activate 'No need, but if you prefer you can
'Activate Auto Filter
If .AutoFilterMode Then Cells.AutoFilter
'Remove FreezePanes
ActiveWindow.FreezePanes = False
'Unhide Columns
.Columns.EntireColumn.Hidden = False
'Delete Empty Columns/Rows if they are all empty
If WorksheetFunction.CountA(.Columns("A")) = 0 Then
Columns("A").Delete
Rows("1:6").Delete
End If
'Get the last Column
iCol = .UsedRange.Find("Sign-Off By", LookAt:=xlWhole).Column
'Start Deleting but from the last to the first (Backward)
For iRow = Cells(Rows.Count, iCol).End(xlUp).Row To 2 Step -1
Set rCell = Cells(iRow, iCol)
'Delete the entire row if it is NOT empty
If Not IsEmpty(rCell.Value) Then
'Deletion
Rows(iRow).EntireRow.Delete
End If
Next iRow
End With
CleanUp:
'Purge Memory
Set wsMilestoneDueDate = Nothing
Set rCell = Nothing
'Restore Screen Updating
Application.ScreenUpdating = True
End Sub

Answer 2

As already stated in comments, the flaw in your code was not looping backwards
But I hereby give you a solution without looping and using one line only, thanks to SpecialCells method of Range object, specifying it to filter cells with some "constant" (i.e. not deriving from formulas) value
Range(Cells(2, iCol), Cells(Rows.Count, iCol).End(xlUp)).SpecialCells(xlCellTypeConstants).EntireRow.Delete
this assumes you always have at least one value below row 1
should not that be the case then just add a check:
If Cells(Rows.Count, iCol).End(xlUp).Row > 1 Then Range(Cells(2, iCol), Cells(Rows.Count, iCol).End(xlUp)).SpecialCells(xlCellTypeConstants).EntireRow.Delete
While looking at your entire code you should adopt the good practice to avoid Select/Selection, Activate/ActiveXXX pattern and Always fully qualify ranges up to their worksheet (if not workbook) parent objects, like follows:
Sub Delete_Signoffed()
Dim iCol As Long
With Worksheets("MilestoneDueDate") ' reference wanted sheet
If .AutoFilterMode Then .Cells.AutoFilter
ActiveWindow.FreezePanes = False
.Columns.EntireColumn.Hidden = False
If WorksheetFunction.CountA(.Columns("A")) = 0 Then
.Columns("A").Delete
.Rows("1:6").Delete
End If
iCol = .Range("A1", .Cells(1, .Columns.Count).End(xlToLeft)).Find("Sign-Off By", LookAt:=xlWhole, LookIn:=xlValues).Column
.Range(.Cells(2, iCol), .Cells(.Rows.Count, iCol).End(xlUp)).SpecialCells(xlCellTypeConstants).EntireRow.Delete
End With
End Sub
as you can see
all range objects (Columns(), Rows, Range, Cells) are referencing Worksheets("MilestoneDueDate") through that dot (.) in front of them
iCol is being set running Find() method in the most restricted range possibile