Bug found while replacing text in formulas - vba

Question

I discovered a very interesting bug today i.e if it is a bug.
Can you please confirm if you can replicate it? If it is a bug and has been not reported then I can file it as such. I am also ok if any of the Excel-MVPs want to file it as a bug.
Let's say in sheet1 in cell A1, you have a formula = $B$2+ $B$3. Now ensure that your cell is selected. Now paste this code in a module.
Sub Sample()
Dim r As Range, sPre As String, sAft As String
Dim ws As Worksheet
Set ws = ThisWorkbook.Sheets("Sheet1")
sPre = "$B$2": sAft = "$C$3"
On Error Resume Next
Set r = ws.Range("A1:A2").SpecialCells(xlCellTypeFormulas)
On Error GoTo 0
If Not r Is Nothing Then r.Replace what:=sPre, _
replacement:=sAft, _
lookat:=xlPart, _
MatchCase:=False
End Sub
Ideally the code should have worked and the = $B$2+ $B$3 should have changed to = $C$3+ $B$3 in the formula bar but it doesn't. It will work only if you step through it or if you do as mentioned in the next line
Now do one thing. Select any cell other than A1 or A2. Now if you run the code, the code works as expected.
At first I thought that my excel has gone crazy so I closed and re-started it but I was able to reproduce the above in Excel 2010 many number of times.
Then I thought it is a .SpecialCells issue but the above behavior can be observed with this code as well.
Sub Sample()
Dim r As Range, sPre As String, sAft As String
Dim ws As Worksheet
Set ws = ThisWorkbook.Sheets("Sheet1")
sPre = "$B$2": sAft = "$C$3"
Set r = ws.Range("A1:A2")
r.Replace what:=sPre, _
replacement:=sAft, _
lookat:=xlPart, _
MatchCase:=False
End Sub
Are you able to replicate it?

Answer 1

I replicated your issue and got away with it by two ways:
Try ThisWorkbook.Save after the replace.
select other cell than A1 or A2 (cell selected whose formula getting replaced) after replacing formula.

Answer 2

While many alternatives have been suggested in the other answers for example
Select another cell via code
Save the workbook
If I do not want to select the cell or save the workbook then is there an alternate way which is better than the above two? Yes, there is. Just tried this and it works
Sub Sample()
Dim r As Range, sPre As String, sAft As String
Dim ws As Worksheet
Set ws = ThisWorkbook.Sheets("Sheet1")
sPre = "$B$2": sAft = "$C$3"
On Error Resume Next
Set r = ws.Range("A1:A3").SpecialCells(xlCellTypeFormulas)
On Error GoTo 0
If Not r Is Nothing Then r.Replace what:=sPre, _
replacement:=sAft, _
lookat:=xlPart, _
MatchCase:=False
r.Formula = r.Formula
End Sub
But the question still remains that the Formula Bar should have updated in the original scenario but it doesn't

Answer 3

I'm partly able to replicate it, also Excel 2010.
If I run the macro with the cell selected, using the Run option within the Visual Basic Editor, the value in the cell changes to reflect the new formula, but the formula in the formula bar doesn't show as updated. But it must be updated because the result changed. If I click out of the cell and back in, the updated formula appears and shows that the search/replace worked.
If I step through the macro in the VBA window, the formula bar does show as updated while the macro runs.
If I run the macro from the Excel window, using Macros -> View -> Run, the formula bar does show as updated while the macro runs.
If I add r.Select to the last line of the macro, running it from VBA works.
If I run the macro so it does not update the formula bar, then click into the formula bar, the formula bar shows the old formula but the cell content changes to show the new formula instead of the answer.
Edit: The behaviour appears the same in Excel 2013