What is a metric for “working”? Diversity training is primarily for corporate and military usage to prevent traditionally bad hiring and recruitment practices, poorly thought out promotions and demerits and such.
Within those organizations, I would say that things are greatly improved to where they were from the 1970s when the big “push” of diversity training began in the US military branches and US corporations.
It was supposed to make it into education but American public schools (K-12) are notoriously conservative (despite pretending to be inclusive) nationwide with very few exceptions.
So if you want to know if it’s working or not, look at differences between the 1970s (when it began) to today and see if there is an income boost among populations thanks to diversity training facilitating awareness of class and race ignorance among human resources and management personnel.
There’s a long way to go yet but there has improvements in these organizations.