Using tiles with transparency causes blending artifacts underneath

I am using an atypical tileset that uses transparency to blend terrain on individual layers. I have four layers on my world map, one for adding cracks to the terrain, and three for the ground. The three ground layers are designed to allow the ability to blend the terrain with the transparency effects:

However, if you look closely, you will find that the bottom-left corner of the newly placed grey tiles appears to have some kind of artifact. Now this additional grey blend actually occurs on the layer below it, because if I place a full green tile on the ground1 layer where the artifact occurs, it goes away.

I haven’t tested this same issue in my game engine because I haven’t fully implemented it, but I would only guess that it won’t cause any issues in-game. But this is an annoying issue and I feel like it might be a bug when dealing with tiles that have transparency in them.

I am using the latest version of Tiled (0.17.0).

Okay, I’ve changed my tileset around to something typical, and I’ve added terrain brushes for each terrain type:

However, I do have a question about the terrain brush. Is there a way to reduce the size, because I’m either using it at a size of 3 tiles, or 2 if I hold down the control key? It’s not a huge deal, but it would be nice to have the functionality if it otherwise does not exist.

I’d guess this artifact is in your graphics somehow, since that would be quite an odd defect. But if you think this may be an issue with Tiled, please share that map and tileset so that I could look into it.

With the way this terrain system works, you can’t ever edit less than 2x2 tiles. This is because it changes the terrain type on the corner, and one corner affects all 4 connecting tiles.