Not working with context conditions

Hi, it appears context conditions (conditions based on existing contexts) are not working when used with Context: Menu Block.

I created a context that sets a menu item to active when a book is being viewed (let's call it Menu book). Then I created a second context to set another menu item to active when the book is not being viewed. This was done using a context condition with the following code:

~Menu book

I'm posting this here, because the context works fine when used on the default main and secondary links.

Cheers