TLDR: Is PTO counted as overtime if I’ve already worked 40hrs in a week?

Newish to this company I’m working for. But I was in charge of running payroll at a different company and this is mind boggling to me. I’m scheduled 8-5:30 5 days a week normally. My supervisor asked me to fill a shift that works 4 10’s but also one of my regular scheduled shifts, which would be an additional 8 hour shift. With a total of 48hrs for the week. Halfway through the week I found out that I needed to take PTO for a family emergency. I got approved to take PTO for my regularly scheduled 8 hour shift. Upon approving my time card, I noticed that my supervisor had not added my PTO. When I asked about it he said “oh we don’t give you PTO if you’re at or over 40 hours because then it would count as overtime.”….. In my experience, the PTO would not be counted as overtime, but actually be listed under PTO and not count towards actual hours worked. Is my boss a dippy or am I mistaken?