Thanks for the reply,
After messing around with some settings from the NavMeshActor, as it turns out, under the generation tab, the tile size was too large. So whenever the game ran, whatever path that was shown in the preview was not true to the path that the AI tried to follow in-game.
After cranking down the tile size (to about 500 or so) the navigation path was much finer and the ai could work its way through tight spaces.