When you’re calculating WACC, let’s say that the company has convertible debt. Do you count this as debt when calculating Levered Beta for the company?

Trick question. If the convertible debt is in-the-money then you do not count it as debt but instead assume that it contributes to dilution, so the company’s Equity Value is higher. If it’s out-of-the-money then you count it as debt and use the interest rate on the convertible for Cost of Debt.