Just found out I’m not getting paid OT

So ya, the title. Ive been taking a class at work, for work, this class takes 2.5 hours a day, 4 days a week. I found out today, that the extra 2.5 hours a day I've been working, while it is paid, doesn't count towards my daily hours worked, so not a single dime of overtime.. honest to god fuck these companies…