Offline fixtures. Help, please.


We just got a new preforming arts center at our local high school. I'm helping the new drama teacher learn the new ETC system. We have an Ion xe. While patching lights and checking in on Concert, some of the fixtures are appearing "offline."  This happens intermittently, sometimes the light are online and working, then the next time we turn on the board, they are not working...because the are offline.

Can anyone help me with this? I'm somewhat new to the Ion xe...but have watched tons of video training on that and on Concert. Help!!!