Chunks of Macro being skipped when running

I have a macro to insert formulas based on specific cell values. The macro run on several sheets.. The second sheet works perfectly and the first sheet works perfectly when ran to a breakpoint. When the macro is run in its entirety the first sheets does not work. If I move the variables it will work once but not again. Any advice would be appreciated.

Sub NewTest()
Dim Response As Integer
Dim LR As Long: LR = Cells(Rows.Count, 17).End(xlUp).Row
Dim i As Long
Dim BR As Long: BR = Cells(Rows.Count, 21).End(xlUp).Row
Dim z As Long
Application.ScreenUpdating = False

' Displays a message box with the yes and no options.
Response = MsgBox(prompt:="Have You Updated Report Pages with Player Numbers?", Buttons:=vbYesNo)

' If statement to check if the yes button was selected.
If Response = vbYes Then

'select Weight Report Sheet
Sheets("Ind-Report (Wt)").Select

'Add Look up Formulas below last months test
For i = LR To 3 Step -1
    If Not (IsEmpty(Cells(i, 17))) Then
        Cells(i, 1).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,2,)"
        Cells(i, 2).Select
        Selection.Formula = "='Recording Sheet WTs'!$e$1"
        Cells(i, 3).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,3,)"
        Cells(i, 5).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,8,)"
        Cells(i, 6).Select
        Selection.Formula = "=iferror((e" & i & ")/(c" & i & "),"""")"
        Cells(i, 7).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,5,)"
        Cells(i, 8).Select
        Selection.Formula = "=iferror(((g" & i & ")*2.2)/(c" & i & "),"""")"
        Cells(i, 9).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,11,)"
        Cells(i, 10).Select
        Selection.Formula = "=iferror((i" & i & ")/(c" & i & "),"""")"
        Cells(i, 11).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,12,)"
        Cells(i, 12).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,13,)"
        Cells(i, 13).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,4,)"
        Cells(i, 15).Select
        Selection.Formula = "=vlookup(q" & i & ",'Recording Sheet WTs'!$A$5:$N$39,14,)"
    
    End If
    
Next i

'Select Field report Sheet
Sheets("Ind-Report (Field)").Select

'Add look up formulas below last months test
For z = BR To 3 Step -1
    If Not (IsEmpty(Cells(z, 21))) Then
        Cells(z, 1).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,2,)"
        Cells(z, 2).Select
        Selection.Formula = "='Recording Sheet Cond'!$e$1"
        Cells(z, 3).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,3,)"
        Cells(z, 5).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,4,)"
        Cells(z, 7).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,5,)"
        Cells(z, 9).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,6,)"
        Cells(z, 11).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,7,)"
        Cells(z, 13).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,8,)"
        Cells(z, 15).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Cond'!$A$5:$N$39,9,)"
        Cells(z, 17).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Shuttle'!$A$5:$T$39,15,)"
        Cells(z, 19).Select
        Selection.Formula = "=vlookup(u" & z & ",'Recording Sheet Shuttle'!$A$5:$T$39,16,)"
    End If
    
    Next z
    
'Clear Last Test Recording forms
Sheets("Recording Sheet WTs").Select
Range("C5:G39").Select
Selection.ClearContents
Range("I5:J39").Select
Selection.ClearContents
Range("L5:N39").Select
Selection.ClearContents


Sheets("Recording Sheet Cond").Select
Range("C5:I39").Select
Selection.ClearContents

Sheets("Recording Sheet Shuttle").Select
Range("C5:J39").Select
Selection.ClearContents

Else

' The no button was selected.
MsgBox "Update Reports then re-click New Test Button"
End If
    
    
End Sub

The answers will come from a little skill with debugging code.

Here are a few tips.

1. Use break points to temporarily stop the process and check to see if it has done what you expected that section to do.
2. On errors, use the debug option. Inspect the variables to see what does not look right.

Dennis - Thanks for the reply. This is were I'm stuck. When I toggle breakpoints to run each part on their own. It works great. When I run the entire macro, I don't get an error message it just does not execute the macro on one of the sheets. It almost as if I could put in a breakpoint permanently in the macro it would work but would be to much of a pain to have as 2 different macros.