[Trouble with Crop]

I recently bought this app and am working on learning it but have hit one trouble with a basic function that I cannot figure out.

 

When I enter Crop mode (C key) and want to set the aspect ratio the application won't let me change the orientation (between landscape and portrait). At the bottom of the window is a 'tip' that indicates that Shift+O would cycle the orientation but it doesn't seem to do anything at all. Typing an O without the shift does cycle through the overlays so the problem seems to be with Shift+O. Any idea what is wrong and how I can fix it?

 

A secondary question is: is there a way to lock the aspect ratio? If I enter Crop mode and select an aspect ratio, then adjust the crop it wanders from the aspect ratio and I have to reselect it from the menu again.

 

Thanks.