for loop anomaly

Hello, I have a code where, when I click the button, the "for" loop goes through some of the data and suddenly jumps out of the loop and gives me the dialog box saying that it's done. In an effort to find out why, I stepped through using F8. Doing that allowed it to finish the "for" loop for all of the data. When holding down F8, it jumped out again. The code is below. I could not find anything like this online. Do I need to slow the code down somehow? Doesn't that defeat the purpose of a macro? Please let me know if you need the full code and a sample spreadsheet. It will take me time to put that together, but hopefully the code below shows some obvious error that I missed.

For x = 2 To lastCol

On Error Resume Next

    If Cells(13, x).Value <= 50 And Cells(17, x).Value = "Solar" Then
        Cells(13, x).Interior.ColorIndex = 45
    ElseIf Cells(13, x).Value <= 50 And Cells(17, x).Value = "Gas" Then
        Cells(13, x).Interior.ColorIndex = 41
    ElseIf Cells(13, x).Value <= 50 And Cells(17, x).Value = "Storage" Then
        Cells(13, x).Interior.ColorIndex = 48
    ElseIf Cells(13, x).Value <= 50 And Cells(17, x).Value = "Wind" Then
        Cells(13, x).Interior.ColorIndex = 44

    ElseIf Cells(13, x).Value <= 100 And Cells(17, x).Value = "Solar" Then
        Range(Cells(13, x), Cells(12, x)).Interior.ColorIndex = 45
    ElseIf Cells(13, x).Value <= 100 And Cells(17, x).Value = "Gas" Then
        Range(Cells(13, x), Cells(12, x)).Interior.ColorIndex = 41
    ElseIf Cells(13, x).Value <= 100 And Cells(17, x).Value = "Storage" Then
        Range(Cells(13, x), Cells(12, x)).Interior.ColorIndex = 48
    ElseIf Cells(13, x).Value <= 100 And Cells(17, x).Value = "Wind" Then
        Range(Cells(13, x), Cells(12, x)).Interior.ColorIndex = 44
        
'There's a bunch more of the same code blocks with values incrementing by 50.
        
    ElseIf Cells(13, x).Value > 600 And Cells(17, x).Value = "Solar" Then
        Range(Cells(13, x), Cells(1, x)).Interior.ColorIndex = 45
    ElseIf Cells(13, x).Value > 600 And Cells(17, x).Value = "Gas" Then
        Range(Cells(13, x), Cells(1, x)).Interior.ColorIndex = 41
    ElseIf Cells(13, x).Value > 600 And Cells(17, x).Value = "Storage" Then
        Range(Cells(13, x), Cells(1, x)).Interior.ColorIndex = 48
    ElseIf Cells(13, x).Value > 600 And Cells(17, x).Value = "Wind" Then
        Range(Cells(13, x), Cells(2, x)).Interior.ColorIndex = 44
    End If
    
'This section inserts vertical lines to better view each entry
    Range(Cells(1, x), Cells(17, x)).Select
    Selection.Borders(xlDiagonalDown).LineStyle = xlNone
    Selection.Borders(xlDiagonalUp).LineStyle = xlNone
    With Selection.Borders(xlEdgeLeft)
        .LineStyle = xlContinuous
        .ColorIndex = xlAutomatic
        .TintAndShade = 0
        .Weight = xlMedium
    End With
    Selection.Borders(xlEdgeTop).LineStyle = xlNone
    Selection.Borders(xlEdgeBottom).LineStyle = xlNone
    With Selection.Borders(xlEdgeRight)
        .LineStyle = xlContinuous
        .ColorIndex = xlAutomatic
        .TintAndShade = 0
        .Weight = xlMedium
    End With
    With Selection.Borders(xlInsideVertical)
        .LineStyle = xlContinuous
        .ColorIndex = xlAutomatic
        .TintAndShade = 0
        .Weight = xlMedium
    End With
    Selection.Borders(xlInsideHorizontal).LineStyle = xlNone
Next x
    
'Color index numbers and fuel type
'solar   - orange    - 45
'gas     - blue      - 41
'storage - grey      - 48
'wind    - yellow    - 44

MsgBox "COD Timeline has been updated."