Atlas Uncompressed when adding detail mesh to terrain.

Can anybody tell me what is this about and how to fix it? i dont recall having this issue in the past.
I did fresh install of unity and no matter which mesh i add, it always gives this warning.

9729367--1391041--Atlast Uncompressed.PNG

Never mind, i kinda firgured it out. Have to disable GPU Instancing when selecting detail mesh. now i can paint.

Use it as a tree in the terrain settings inorder to bypass it