Seems they have changed the way followers are handled when using fast travel, again. Last patch they added some code to make any player teammate follow the player when he fast traveled providing their waiting variable wasn't set to 1. This caused problems for one of my mods, and will likely effect any mods that try to manage companions from other mods as we don't have access to those companions script variables.

In the latest patch I have noticed a new behavior when fast traveling with companions. For testing I am using Cass (vanilla companion) and a custom companion of my own making. Both are player teammates, and are in follow mode. Now when I fast travel with them only one of them actually comes with me. Seems to be the one that was following at the closest distance. Moving through a load door makes the other finally catch up. I'm only guessing here but possibly they made it so that now only one human and one animal companion can fast travel with the player. Can anyone else confirm this behavior that is using some kind of multiple follower mod?

I just don't understand why they have to keep messing with something that wasn't broken in FO3.

This was present pre patch with an unmodded, vanilla game.

I have Boone & Ed-E, sometimes I'll go through a door and only one will warp with me until I move further from the door at which time the other will warp in.

I'm fully patched and just went to test this out as I did have only one of my own modded followers active with my current character. I'm having no problems with two of my own humanoid followers (I went and picked up my second one) and no problems with Cass + one of my own followers (went and dug up a different character with Cass hired). Mine are set to playerteammate just like the vanillas. With Cass + my follower I did both default and long follow distance with no issues.

Yep you're right. I had Cass in waiting mode and was adding the follow package through my mod so no wonder she stopped moving with me. I still don't like this whole "waiting" variable.