Drop down icon is ‘misleading’.

When I select the Audio Mixer asset in Project Browser (without any other channels apart from the Master Group) I see a drop down menu in Audio window. As a user I thought that I could click on this and then be able to ‘switch’ to the other Audio Mixers. Please see attached screen shot for details.

To reproduce:
- Create multiple Audio Mixer assets
- Double-click on one of them to open the Audio Mixer window
- Click on the top left drop down icon
- Observe that there is no list or context menu

Expected result when there is only one mixer > No drop down icon
Expected result when there is more than one mixer > Drop down menu