User is in a remote control with a customer. The user clicks Alt + Tab to refer to another application they have open. The customer attempts to use the keyboard and is getting no response.
This is working as designed. Since this is a remote control session, the customer is receiving input from the user keyboard. So on the customer side, it is waiting for an ALT + to be entered. If the customer hits Alt key again, they will be out of the Alt command and be responsive again. If they haven't done this and say hit E on their keyboard or a command that the current program that is active on the customer screen, it will respond as if ALT + E had been used.
Avoid using the Alt key unless it is necessary when doing a remote control session