I've found with some disappearing companions, it's usually to do with a quest. I had dismissed Nick to Sanctuary and he wasn't there.. Turned out he was at the starting point for another quest I was in the middle of but didn't complete.
Companions like Nick or Piper that have a home base, when you press the cancel button when the list of places to send them shows up they'll go back to their home bases. Nick to his office, Piper to the paper.
I lost Strong for a while and it pissed me off. Then one day I took a nap in the highrise I made for myself in Sanctuary and I could hear him bitching outside when I woke up
Ugh, apparently the recent update that brought in the in game modding tool now makes it so achievements are disabled if you have mods on, never did this in the past games and were able to get mods from other means before this was put in and get them, but now, blah....
I booted up the game to download the latest update and decided to just start a new game with a female character. I'll probably switch back to my level 49 dude when Far Harbor drops, but its nice to go back in these games and try different shit.
Okay so I've been playing through this. I've avoided other posts though so nothing gets spoiled.
I feel like a bit of a bastard. I've sided with the Institute. I've already turned the BOS against me and plan to do the same with the Railroad. But I hate the Railroad. Self righteous assholes. But I've sided with what appears to be the bad guys.
I finally wrapped up my main story. I joined every faction I could. Then betrayed The Brotherhood and took down The institute with The Minutemen. Taking a break from it to play Uncharted. Then going back to wipe out the BOS
The Automatron one is pretty cool if just to build awesome robot companions. I haven't played a ton of Far Harbor, but the setting is pretty cool and they are setting up an interesting story, though it seems to be heading towards another "you have to pick a side" conclusion which I don't like about Fallout games.
I kind of wish I could find better armor somewhere because my character is still wearing his Vault jumpsuit since I've upgraded it so much and I'm kind of sick of looking at it.