Okay, so many people on various forums are also reporting the same issue. I'm not overencumbered, there are no enemies near me, I'm outdoors but I can't fast travel. I get the 'fast travel is unavailable from this location' message no matter where I am located. I'm assuming this has something to do with where the game thinks my player is, though I have no idea how to to check this. This is a serious hinderence to my game experience, I'm not going to lie, it very serious hinderence my game experience.
If I thought it was only me with this issue I wouldn't be posting this, but it's an issue that seems to be on all platforms. So Patch please!