Reproduction steps:
1. Open project attached (TileBug.zip)
2. Change Sprite draw mode size to 128x128 (Error: "Cannot generate 9 slice most likely because the size is too big. Requires 65536 vertices and 98304 indices")
3. Press play or reopen scene.

Expected result: Game starts normally and sprite renderer will not change.
Actual result: Sprite can not be seen, warning "Incomplete mesh data in Sprite. Please reimport or recreate the Sprite. UnityEditor.DockArea:OnGUI()" appears every time editor is updated.

Note: After changing Draw Mode size, warning does not appear.

Reproduced on: 5.6.0b3, 5.6.0b11, 2017.1.0a3.