macOS - mask attack doesn't work

[magnum]

Apple's OpenCL runtime started out as crap, then it got better and better until Yosemite, at which point it was quite good (all JtR OpenCL formats ran fine on my laptop). Then with El Capitan it got really bad again and with Sierra things aren't much better. Unfortunately there isn't much you can do - we are stuck with whatever version Apple feeds us.

You could submit bug reports to Apple but I have a feeling piping them to /dev/null will be just as effective.