Odd behaviour by automatically changing color of certain characters in a cell

Question

I'm facing a odd behavior by applying different colours within one cell via VBA.

In my case there are hundrets of cells within one column, showing different work-packages. My vba code exaclty does what it should do, by coloring identified strings (respecively work packages) via looping through the cells and identifiying each work package via RegExp.

Here there is one extract that is doing the coloring job:

Set objRegex = CreateObject("vbscript.regexp")
With objRegex
    .Global = True
    .Pattern = suchmuster
    If .test(objWks_myTable.Cells(row_myTable, 20).Value) Then
        Set RegMC = .Execute(objWks_myTable.Cells(row_myTable, 20).Value)
        For Each RegM In RegMC
            objWks_myTable.Cells(row_myTable, 20).Characters(RegM.FirstIndex + 1, RegM.Length).Font.Color = vbOrange
        Next
    End If
End With

The issue appears as soon as I double click the cell after my makro run. Then without any recognizable pattern, some characters are shown in a different color (mostly not only one character but a connected bunch of). In the picutre, the first cell shows the colours after my vba run, the second cell shows how it will immediately look like, if i double click it. If I leave the edit mode via Escape, the original vba set colors will stay, If I leave the edit mode via Return, the undefined changes happen. There are no formats nor format conditions set within the cells.

I really need somebodys help here. Would be great to find a solution! Many Thanks !

1. This picture should show the issue: Picture of the issue

Answer 1

I've found the issue. First I tried also Instr instead of using a RegExp but the issue didn't disappear. So I was investigating in my code that writes the strings into the cells. And within that code I did the following:

 dummy = dummy & " # " & z_trim(ctrl.Caption) & vbCrLf
 ActiveCell.Value = dummy

The issue is because of vbCrLf

If I write the strings into the cells the following way, the changes within my coloring run are fixed, there is no change by entering the cell in edit mode:

   dummy = dummy & " # " & z_trim(ctrl.Caption) & Chr(10)
 ActiveCell.Value = dummy

Picture of fixed issue

It works, so I'm fine. But still interessted, why vbCrLf is causing such confusing thing?