There seems to be a issue with 4.14’s transform for grass that is generated with grassmaps in the terrain shader. Only some grass around the map has a squashed look / looks like one axis is flattened. This is the same regardless of the model used. It happens in our projects on some bushes also.
This is obvious in various Marketplace Packs and Epic’s Open World Grass.
Switching back to 4.13.1 and this issue doesn’t occur. My guess it’s due to recent changes to the SceneComponent Engine class. Note that it doesn’t happen to manually painted grass, only grass maps in the terrain shader.