Sculpting Causes Crash On iMac

Whenever I click on my terrain to sculpt Unreal crashes. I have a flat terrain 127 quads/section, 2x2 sections/compontent, 32x32 components, or 8128x8128 pixels. I started with the 3rd person example, deleted the walls and floor, and added a terrain, and just used the supplied grass. I have unreal 4.14.0 on iMac os Sierra 10.12.2. Whenever I select the sculpting tool and click on the terrain, or do a control-click, unreal crashes.

OK. So I deleted the terrain and recreated it. I can now edit it.