Excel 2010 - clearing autofilter conflicts with setting font color in VBA

Question

I have a client who uses Excel 2010 and has no plans to upgrade. I've built a fairly complex spreadsheet for the client that includes several tables and a significant amount of VBA code. Some of the columns in the tables permit autofilter and some of the custom formulas for the table cells change the cell's font color.

We're seeing a conflict between clearing the autofilter and the VBA code that sets the font color. Specifically, if the filter is cleared, then an error

-2147417848 Method 'Color' of object 'Font' failed

occurs in the VBA and, more importantly, from that point on the border around any selected cells is no longer shown which makes the sheet difficult to use. We've also seen corruption of the workbook. Even if the error is ignored, the selection border problem occurs.

I've stripped down the large spreadsheet to a very simple one to illustrate. Obviously this is not the real world code but it does exhibit the same problem.

As can be seen, the formula in cell B2 is "=changeColor(A2)"

The code for "changeColor()" is:

Public Function changeColor(t As String) As String
    changeColor = t
    If t = "Fred" Then
        Application.Caller.Font.Color = vbBlue
    Else
        Application.Caller.Font.Color = vbRed
   End If
 End Function

This all works perfectly until an autofilter is added and then removed. i.e.:

1. Click on the down arrow in the Name column header and amend the filter to exclude "Sheila". This works as expected and row 3 is no longer visible.

2. Click on the down arrow again and "Clear filter from Name". The row is now visible BUT selecting cells with the mouse no longer shows a border around those cells (although they are in fact selected). The VBA Immediate window confirms that the "Method 'Color' of object 'Font' failed" error occurred.

If calculation is set to manual while the autofilter is cleared, then no problem is seen. If "changeColor" is modified so that the Font.Color property isn't changed, then no problem is seen.

Does anyone have any idea how to avoid this situation? It does not occur in Excel 2013 so presumably is a 2010 "feature". Should I be using different code to set the color, or is there a way to detect that the code is being run while a filter is being cleared? Any ideas would be greatly appreciated.