Can I have more than 16 transparent icons in a ccomboboxex?

See more:

C++

MFC

It seems that there is a limitation to 16 transparent icons you can use in a CComboBoxEx. I have the following pseudo code (I am adding the same icon but you get the idea):

HICON hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME)
m_ImageList.Create(16,16,ILC_COLOR32,20,1);

for (int nImage = 0; nImage < 20; nImage++)
{
    m_ImageList.Add(hIcon);
}
m_cmbAction.SetImageList(&m_ImageList);

The first 16 icons are OK - the following ones all have a black background instead of the transparency. The same code with an Image list associated to a CTreeCtrl or a CListCtrl works beautifully. I know it sounds crazy but any ideas? Thanks in advance

I am using Visual Studio 2013, Windows 10.

What I have tried:

If you want to reproduce, you can download the code from here http://db.tt/ewe3wsQ7gQ

Adding ILC_MASK to the CImageList::Create does not help (and according to some sources should not be used with ILC_COLOR32)