Had this problem yesterday. After memory mission, where you are walking in Kellogg's mind, i met Valentine. After dialog with him, i left the building, and after some playtime i've realised, that he is not following me. I returned there, and he was just standing still. I couldn't talk to him, (dialog wheel appears, but you can't talk to him, only trading), he wasn't following orders as well. Then i've tried to take piper with me, so valentine'd go back to the detective agency. After these actions i realised, that talk option in the chat wheel is not working with any of in-game companions. When you press talk option, there is just a beep sound and chat wheel dissappears. Trade option works badly as well, only after 4-5 retries. I surfed the internet, and found out information, that the thing occrus, when you have unfinished dialog with some quest NPC"s. So in most cases, you can just find that npc and finish the dialog, but in my situation, i had not any unfinished dialogs, so it's not solution for me. But i'm sure a lot of players have this problem, it's not some kind of a rare bug. Hope you'll fix it in the final release if this patch.

Sorry if my english is not really good, i'm not a native speaker