Right this issue occurs whenever you attempt to leave the zone, not when moving between rooms. You cannot get to the puzzle room because there's a 'zone transition' door which you need to pass, indicated by the 2-gear pointer icon. When you attempt to interact with the door to transition out of that area, you are met with the dialogue cinematic, and upon exiting the cinematic, you are right back in front of the door. You can use map waypoint travel, but since you haven't yet been to underdark, you cannot jump ahead. If a picture is worth a thousand words, a video should do the trick.Video evidence
[Edit] Sorry, I don't normally bother with all this, and am not used to posted videos. If there's a better way than using google drive links, let me know. I just want this game to be the best it can be and thus I'm attempting to properly capture the bug.