I've placed two businesses in my world, a gym and an arcade, both with lecture whiteboards. I assigned sims to run them, and then switched to a household unconnected with the businesses. I went to the businesses, paid admission, and asked to start a class (a Fitness class at the gym and a Gaming class at the arcade). The class started and the goals appeared, but nothing I did made the goals mark off, and after about an in-game hour, I received a popup saying the class failed because no one attended. I do not have a shoe rack or "No Shoes Allowed" sign on either lot (relevant because I know that can make classes fail). I've tried this with mods disabled. I've attended classes in the past without any trouble, including on the arcade lot that now isn't working.
Edit By crinrict: Added pack tag to title, adjusted title
