So recently got dragonborn and some new mods. Had dawngaurd already from before. But while playing this time, I have come across inns (the Nightgate Inn and Old Hroldan in) which I can enter but am seemingly not able to get out as the door is missing; (rather) the door's exit function (no exit prompt, zilch). I thought it was coz of mods so played once without any active mods but still the same issue. Then thought about the no clip command, used it and realized the original inns ' exit are still there but they seem to be existing beyond my immediate playable area and are in some kind of a void space. teleport works. Would appreciate any possible explanation/solution to this as its a real immersion breaker.

When you tried playing without mods, did you create a new character or use an existing save?

When you play with mods and disable them, the problems they introduced are "baked" into your save. You should try again, without mods and by creating a new game.