So far I've found most of the unique merchants and after trying to send them to my settlement they just dissappear. Anyone else having this issue? I'm on the xb1.

The only one I have managed to find, in Good neighbor, is the Vault Tech Rep.
It always takes a few days for him to get to .

I recommend escorting such to where you want them to go as they are not essential in the base game.

I only met The Scribe once in a pre patch game, and have never encountered him since.