I guess it's Maxson, so apologies. Anyway, I found him back in the Prydwen after Mass Fusion, and he gives me a mission to go to the Institute and get Li, but it is instantly failed because after Mass Fusion, you can't visit the Institute. So, I reloaded before Mass Fusion, and again he is gone. Where do I find him so I can complete that mission before I lose the ability to fast-travel to the Institute?