Mesh Edge Overlap Bug?

Hello,

I am producing terrain tiles and there are some patches that don’t align even if their coordinates are same.

I have triple checked my code and data and it seems valid.
Also KML of the tiles seems correct.

I am attaching sources

An example: At the corner of tiles 1/2/1 NE and 1/3/0 SW corner is placed a bit off upwards.

data.rar (26.9 KB)