What topic is your course on? What language are you teaching?
Udemy is a marketplace (whether you're in UB, PP, or the wide marketplace). We all compete against each other for students' attention. Not everyone can get it.
It's hard for me to tell if you have the best course in a topic and are simply not getting attention, or if you don't have the best course, without seeing it.
PP is only about 15% of overall Udemy consumer marketplace. That is, the marketplace is 5X larger than PP.
It's not simply a matter of "top instructors" or "small instructors" either. It's a race. We're all racing. Are you faster than me?