Could you provide the name of the lab and the steps taken to reach the problem? As far as I understand, QoS features should not be disabled unless there was an absolute need to disable it.
Also please ensure you book an HW based lab as opposed to an software only reservation based lab.
I was trying to enable QoS Policy maps but I'm getting a staus as enabling_failed/disabling_failed. I am trying to build a app which requires me to enable/disable QoS policy maps. I tried both reservation as well as always on lab. Is the QoS feature disabled in sandbox?