Do until loop that doesn't seem to end

It worked once and found the forth valid cell in the range, ever since then it starts and then excel stops responding.

I'm guessing there is no end to the loop but not sure,can someone tell me whats up with this code please?

Sub foo()

Dim UserId As String, CaseId As String, SearchString As String
    
Dim DocGrid As Worksheet, S2LI As Worksheet
Dim CellRef(10) As Range
Dim RowNumba As Long, i As Long, x As Long

    Application.ScreenUpdating = False

    Set DocGrid = ThisWorkbook.Sheets(1)
    Set S2LI = ThisWorkbook.Sheets(2) ' Set the worksheet, Change to suit
        
    UserId = DocGrid.Range("Q3").Value
    CaseId = DocGrid.Range("R3").Value
    SearchString = UserId & CaseId
    
    If DocGrid.Range("R3") = "" Then
        MsgBox "Complete Case Reference"
    End If
        
'   Change the (2) below to the column number you're searching (2 = B:B)
    RowNumba = S2LI.Columns(2).Find(What:=SearchString, LookIn:=xlValues, LookAt:=xlPart, _
        SearchOrder:=xlByRows, SearchDirection:=xlNext, MatchCase:=False, SearchFormat:=False).Row
    
    For x = 0 To 10
        Set CellRef(x) = S2LI.Cells(RowNumba, 53 + (x * 4))
    Next x
    
'Pastes Template Letters Into Their Relevant Column in "Database" Tab
    For x = 0 To 10
        i = 12
        Do Until IsEmpty(CellRef(x).Value)
            With DocGrid
                ApplyMyFormat (.Cells(i, 7).Resize(1, 3))
                ApplyMyFormat (.Cells(i, 10).Resize(1, 3))
                ApplyMyFormat (.Cells(i, 13).Resize(1, 3))
                ApplyMyFormat (.Cells(i, 16).Resize(1, 4))
                .Cells(i, 16).Resize(1, 4) = CellRef(x).Value
                .Cells(i, 7).Resize(1, 3) = CellRef(x).Offset(0, 1).Value
                .Cells(i, 10).Resize(1, 3) = CellRef(x).Offset(0, 3).Value
                .Cells(i, 13).Resize(1, 3) = CellRef(x).Offset(0, 2).Value
            End With
                i = i + 1
            Loop
        Next x
    Application.ScreenUpdating = True
    MsgBox "Done Muvva Funka!!!"
End Sub

Sub ApplyMyFormat(myRange As Range)
With myRange
    .HorizontalAlignment = xlCenter
    .VerticalAlignment = xlCenter
    .MergeCells = True
    .WrapText = True
    .Borders(xlDiagonalDown).LineStyle = xlNone
    .Borders(xlDiagonalUp).LineStyle = xlNone
    With .Borders(xlEdgeLeft)
        .LineStyle = xlContinuous
        .Weight = xlMedium
        .ColorIndex = xlAutomatic
    End With
    With .Borders(xlEdgeTop)
        .LineStyle = xlContinuous
        .Weight = xlMedium
        .ColorIndex = xlAutomatic
    End With
    With .Borders(xlEdgeBottom)
        .LineStyle = xlContinuous
        .Weight = xlMedium
        .ColorIndex = xlAutomatic
    End With
    With .Borders(xlEdgeRight)
        .LineStyle = xlContinuous
        .Weight = xlMedium
        .ColorIndex = xlAutomatic
    End With
    .Borders(xlInsideVertical).LineStyle = xlNone
    .Borders(xlInsideHorizontal).LineStyle = xlNone
End With
End Sub