I have the following code which works fine for retrieving the cursor position as pixels:
Declare Function GetCursorPos Lib \"user32\" (lpPoint As POINTAPI) A         
        
Use ActiveWindow.RangeFromPoint to get the cell address.
Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
' Create custom variable that holds two integers
Type POINTAPI
    Xcoord As Long
    Ycoord As Long
End Type
Sub GetCursorPosDemo()
    Dim llCoord As POINTAPI
    Dim rng As Range
    ' Get the cursor positions
    GetCursorPos llCoord
    ' Display the cursor position coordinates
    'MsgBox "X Position: " & llCoord.Xcoord & vbNewLine & "Y Position: " & llCoord.Ycoord
    Set rng = GetRange(llCoord.Xcoord, llCoord.Ycoord)
    If Not rng Is Nothing Then
        MsgBox "Cell under mouse is :" & rng.Address
    Else
        MsgBox "Not a valid location."
    End If
End Sub
Function GetRange(x As Long, y As Long) As Range
    Set GetRange = ActiveWindow.RangeFromPoint(x, y)
End Function