Thank you for the detailed repro steps, UFO. Seems like I made a minor mistake in a recent update that causes this inconsistent issue. The reason is that the BaseEdges of BP_GridManager are not entirely consistent before and after the GenerateGameplayGrids, which results in inconsistent results for BP_GA_Tile, which looks at this array when generating its edges. I don’t think these issues will exist in a packaged project, but they can appear if you switch back and forth between pregenerated grids. This minor change is needed to fix that (fixed version on the right):
There is a second issue here with the inconsistent corner blocking. This is again due to a sloppy oversight on my end in a recent update. The walls need to be set up so that they block edges between the tiles passing through this tile’s corner. To fix this, change all the diagonal edges for the thin, blue wall actors to ‘-1’ instead og ‘0’, like so (fixed version on the right):
Both of these issues are caused by some embarrassingly sloppy mistakes on my end, so sorry about that, and thanks for pointing them out.