The Stonemason industry does not have any visitor or job class array defined which is apparently resulting in no visitors or employees.
Adding temporary class arrays did not increase visitor/commuter count, so there may be something else at play here. (I also remembered that I am not playing on the master branch, so I will have to double-check some things.) Nonetheless, the Stonemason probably should have those arrays defined for balance.
It's a recent addition, so that must have been missed. Might need to check the Natural History Museum that was added at the same time too.
submitted a PR to correct this. Thanks for the catch !
I could not find the pull request, but I have integrated this fix manually. Thank you for the report and fix respectively.