Last night after completing several story line missions I had Nick, Dogmeat, and Danse all come up missing. Nick and Dogmeat came up after the mission where you track down Shaun's kidnapper (I can't think of the villain or mission name). I sent them both to Oberland station. Danse came up missing after the BOS mission (I can't remember the name of the mission either) where you take Fort Strong. I sent Danse to Sactuary Hills.

I've tried waiting, resting, fast traveling, and using the bell and siren to try to get them to show at every settlement I have but to no avail. I also looked in Nick's office, the Pryden and airport, and several of what I thought my be locations of interest to them. Any help on this?

Sometimes they are in their next spot ready for the next mission. You will find him eventually.