Curious to see if others have seen this issue:
This is a potential minor bug in the new App Options feature found in the App Information pane.
The slider for selecting a tint/shade has to be moved far to the right well outside of the expected range to get the appropriate value. If you select a value inside the expected range it will be black. This is true for both the Background color options and the Font color option.
See images below.
I have submitted a ticket with Qlik will update with their response when I get it.