Did you try un-linking and re-linking the characters (dragging the portraits)? All non-lead character in a group should follow, unless the leader is sneaking.
I take it it doesn't matter which companion you switch to, or who you choose for the main character?
Try verifying local files: in the Steam library, right click on the game and select Properties, switch to the Local Files tab and then click on the 'Verify Integrity of Game Cache...' button.
Try creating a new profile, then starting a new game to check.
It does not mather, where I have my character, or what party character I choose. Linking and de-Linking does not help eather. I will try to verify the local files and if that does not help I'll try to create a new Profile...
dumb question: can I use the same savegame with another profile? I know for the *bug* I'll first try a new one, to check if it has something to do with the save file itself. Thx for the quick answer!
Edit 1: One file was *broken* (sry everything is in german for me so some translations are hard) and got changed. statred the game with my normal profile-> still the same bug. off to try new profile after redoing the file thingie.
Edit2: Of cause with the new profile, everything works guess I gotta replay all again... maybe I'll just wait for next patch, or I'll play with the broken one.