is this a known bug that has been patched or is it something to do with my system? often fixed when going to rest and coming back but not having to take that extra step would be nice

I, personally, have never heard anything such as this so I doubt it is a known bug.

What is your operating system?

On windows 8 and 10, enabling "legacy components" usually solves many problems.

This has occurred in several of my playthroughs, especially when I play a 'talkative' character. Reloading the game usually fixes the issue in my case. I think you can just save after a person you're trying talk to is not responding and then simply reload (you can also try to do that outside of the building and then enter back). I don't know whether there's any solution to that, but it doesn't bother me that much.

I'm using Win 7, by the way.

This is a common bug with game engines of many kinds. It's to do with interactibility with characters or objects, or rather the lack of. An example is the blacksmith in Kaer Trolde in The Witcher 3. The usual 'cure' is to save the game and then reload. As I said, it's a game engine thing, but I have no idea why so many engines display the same behaviour. It's a mystery.