Hi everyone!
Since the latest June 2017 WAB update I have been unable to select which type of theme I would like on a new hosted WAB application. The theme tab is just empty:

This only appears to be happening with newly created WAB apps. I am able to go into existing WAB apps and select themes.
I did recently setup some organisational "shared theme" colours, could this have something to do with the problem? I looked to see if there was a "reset to default" option or similar for shared theme, but there is nothing.
Does anyone have any suggestions?