I did catch the Twitch stream that they discussed that on then got caught up in work and completely forgot to check it out! I glanced at it briefly today and it seems much more complicated than 's solution with all the quad trees and procedural generation. I will likely look into it more in the future because it does do some things I really like. I followed your Map Generator work while I was researching grid based pathfinding before and it looks amazing. Really looking forward to seeing it finished. 
: Thanks for the reply! For whatever reason I assumed that placing walls on the outside of tiles would mess up pathfinding somehow, because it’s as if they’re being placed on nothing at all? But glad to see that this solution works.
Sorry about being a bit unclear earlier, I actually do not intend to do any procedural stuff. I need the dungeon rooms to be modular because I intend to make a simplified in-game dungeon editor where the player can drag and drop preexisting modular rooms onto the grid and build a dungeon that way. I did take a step in that direction however by simply importing my own custom shaped collision pieces and placing them around the manually laid tiles. Right now the walls are a bit huge so they block line of sight since my grid assets are based on a grid with a tilesize of 32, so your guy’s a bit big. I shaved off the corners so the line of sight calculator would work properly.
I briefly messed with the “Make Composite Blueprint” option. Apparently it’s been moved to the Blueprints menu in the toolbar at the top and renamed to “Convert selected components to Blueprint Class” according to this post: Where is "Replace with Composited Blueprint" in 4.7 Preview? - Blueprint - Epic Developer Community Forums
I tried it out after selecting a group of tiles along with one of my custom walls, but the tiles just vanished, so not sure what’s going on there. Once I get some more free time I plan to mess around with it some more though. Also, how difficult do you think it would be to implement pawns/units that are larger than one tile?