I'm playing the script corporate_leadership.txt. My units are not training. It is 1993, three years underway, and some of my retail stores, like this one, have been paying the maximum for training expense since the start. Yet none of my firms' units have gained experience.

I started a new game, from my default script, setup a retail store, maxed the training, ran it for 4 years, and still no training. So, I believe the problem is re-creatable.