Gaia not blending terrains when building 80x80 tiles with tile size 256

[nhunter]

 

[Bryan]

You could use the terrain stitcher. 
If you open the Gaia Manager - Advanced - Tools - Terrain stitcher and then stitch your terrain this should be fixed. 
You should only need to do a very small value. 

I always recommend making a backup of the project just in case.