In 11.0r7 you could set up the separation style in a way that fails to print your Black separation.  There is a different way to achieve the correct result.

Summary: When the intent is to print Black + Spot inks there are two ways you can configure the separation.   One way doesn't work in 11.0r7.

If you create a separation style that has CMY set to "No," and K & Spot set to "Not Blank," and run a job with K and Spot, the K separation is not produced. If you set all of the separations to not blank, and run the same job, then you do get the K separation.

Description of the method that does not work:

K+Spot = Not Blank. CMY = No.  

No K separation is produced.  See the picture below.

Description of the method that works:

CMYK+Spot = Not Blank. The K separation is produced.  See picture below.