I had a clinic set up like yours. They decided to supervise me doing the exercises about 4 weeks in after ignoring me the whole time, and then told me I was doing most of the exercises incorrectly. I didn't go back after that. At the time, I was going to help with posterior tibial tendonitis in both ankles.

(I was irritated enough when he made me run on the first day (at this point, I could barely walk without pain) and then claimed that I was obviously in pain because I ran like a cow. Sorry, sir, I'm running like a cow because this HURTS LIKE ****)

I don't mind if they walk away, even to see other patients (at my current PT, all of the appointments overlap) - but if they walk away to stand around and chat, at least watch me as you're doing nothing.