My main quest progress: I found institute already
Nick: I got his perk (which I finished the 'long time coming' quest) and sent him back to his office right after that.
Yet I cannot find him in his office... I even fool are for over a week! (Game time)
No idea what can I do now....

PS. If there will be a new patch (or dlc include this), I hope we PS4 or XBox players can locate or companions on pip-boy...