Should you be monitored during an entire CoolSculpting session?

For my first chin session, the aesthetician stayed and there were no issues. The second (on the new system), she left and it was more painful. At one point I was going to call the front desk to end it but an alarm went off. I thought she’d return but she didn’t for another five minutes. The pain eased and when she returned, she said the machine stopped with 92 seconds to complete freeze (with 6:28 on clock)? I’m wondering will it still work and should they have stayed?