Legal Question in Employment Law in California

You are an employee.

You are correct that you must be either an "employee" or and "independent contractor."

Your understanding may not be correct as to your status, however. Not all "employees" need to be invited to a "employee meeting." If you are paid with a W-2, there are likely withholdings taken from your check -- meaning your employer is paying you as an employee. Employees can be paid hourly, and the fact that you receive benefits suggests you are indeed an employee in the mind of your employer.

A "mandatory meeting" may also mean that your employer views you as an employee. Your terms of your agreement with the person for whom you perform services will determine if you can be let go for not attending or other act (or failure to act) -- regardless of your status as an employee or a contractor. There also are insufficient facts to determine the strength of your claim that you are a contractor and not an employee -- though the acts you provide clearly suggest that the other side views you as an employee and you are accepting that treatment by allowing yourself to be paid as an employee.

Your question was can an employer require an independent contractor to appear at a meeting.

I would look at it as a practical matter. If I am an independent contractor and the person who I am doing work for wants to meet and is calling it mandatory, then it is of obvious importance to them. As a independent contractor this is my customer. I would suggest that you meet reguardless. I would want to keep my customer happy.