ComboBox does not responds to mouse wheel rotation

Hi there!

I have noticed a weird combobox behaviour: combobox stops to respond to wheel rotation after text changing.

How to reproduce:

Dim array() As String = {"First", "Second", "Third", "Fourth", "Fifth"}
For i As Int32 = 0 To UBound(array)
    combo.Items.Add(array(i))
Next
combo.AutoCompleteMode = AutoCompleteMode.SuggestAppend
combo.AutoCompleteSource = AutoCompleteSource.ListItems

Now run it and try to type in the combo's text field a letter, some items starts with, let it be 'F'. During typing suggestions dropdown list appears. Click on any suggestions item (let it be 'Fourth') - it will put item's text into text field. And try to rotate mouse wheel now: combobox have locked at 'Fourth' value and will not to switch to other items.

But combo could be switched by pressing down arrow and selecting items by mouse click.

What this means?