I believe even Sandy King, the person who invented the Pyrocat developers, used the very same technique. Not sure what film he used, but that particular combination of BTZS tubes and Pyrocat has been used by many large format photographers.
Are you getting the developer evenly distributed across the film, and quickly enough when you start spinning the tubes in the water bath? Do you agitate vigorously in the stop bath period? Is the fixer applied uniformly and quickly enough on the entire film? Lots of questionmarks that don't have much to do with your actual materials, but rather the technique used.
Do you have the same problem when using film other than Efke?