Brush tiles when moved near edges while height is set to 600

Steps to Repro:
1. Create a new Project or open attached Project
2. Hierarchy > right-click
3. 3D Object > Terrain
4. Paint Terrain > Set Height
5. Set Height to 600 and Click Flatten
6. Select a brush and move towards edges

Actual Result:
Brush tiles on moving to edges

Expected Result:
Brush shouldn't tile when painting on edges

Reproducible with:
2019.2.0a10, 2019.1.0b10, 2019.0a1, 2018.3.8f1, 2018.3.0a4

Note:
New Terrain tools were introduced from 2018.3.0a4

Environment:
Windows 10, Mac 10.13, and Mac 10.14