Unable to change texture's "Size" and "Offset" Value through dragging "X" and "Y" properties

Steps to repro:
1. Open attached or create a new project
2. Hierarchy > right click
3. 3D object > terrain
4. Select paint texture from paint tab
5. Edit terrain layer > Add a layer
6. Create a layer through Add terrain layer window
7. Select the newly created layer in Project window
8. Try to drag Size "X" or "Y" property

Actual Result:
1. Property value slider tool doesn't come for texture layer asset file
2. X and Y property name is not listed next to offset input fields

Expected Result:
1. Values should change when "X" or "Y" property is dragged (Similar to a materials offset property)

Occurring with:
2018.3.0a6, 2018.3.0a5, 2018.3.0a4

Note:
New Terrain tools and texture layers are introduced from alpha 4

Environment:
Windows and Mac