This feature would be particularly useful when you have an audio attachment that is quite big. It shows you the 'audio' icon. In order to overrule this I had to add an image that is even bigger than the attachment which blows the note size unnecessarily up.
Found WORKAROUND:
So - size doesn't matter apparently. Whatever your algorithm is doing it has nothing to do with file size when there are audio & image files present.
First: insert the image you want to see in the snippets view for example.
Second: add your audio file.
P.S.: This is for the PC version