My machine has 8 cores. I have tried changing the number of workers in parallel preferences, tried making a new local profile, tried parpool(8); none of these seem to work. I have Matlab 22.214.171.1241360 (R2016a). My machine has windows 10. I tried parpool on a different machine with 16 cores and Matlab 2016a, encountered the same problem. On this machine, the validation step of a new cluster connected to 16 workers in job test and SPMD job test, but back to 1 worker in actual parpool. I checked bug reports, and this does not seem to be a known bug. What can I do to use the maximum number of workers?