You have to do it at the beginning of an activity or by using multiple devices in an activity. When you press a button in an activity it will send a command from each device (each column on the setup page) that has a command defined. You shouldn't need to do that in this case.

Try it with the Tivo remote and see if you get the same behavior relative to turning the TV off and back on. Nothing you do with the TV should interfere with the Tivo hack. If it is then the TV power commands must be resetting the 30 second skip somehow.