Is a professor obligated to provide feedback on an assignment?
Giving good feedback is good practice. However, people working at the university have multiple responsibilities and they need to make trade-offs. So it is very well possible that your professor made a legitimate choice, we don't know and neither do you. Moreover, professors have substantial freedom in making those trade-offs. So there is very little you can do to force him to give feedback. Trying that will certainly back-fire. Instead, your best bet is to politely ask for an appointment, and be flexible about when that appointment takes place.