The tree's default selection functionality stops working when switching between 2 terrain game objects

Steps to Repro:
1. Open attached or create a new project
2. Hierarchy > right click
3. 3D object > Create 2 terrains
4. Select 1st terrain and select paint tree tab
5. Edit tree > add tree >
6. Add any prefab or speed tree from assets
7. Select 2nd terrain > select 1st terrain

Actual Result:
1. The tree is deselected under paint trees tab
2. It's also not selecting by default when paint tree tab is switched from another terrain tab

Expected Result:
1. The tree should remain selected after switching from another terrain.
2. On selecting "paint tree" tab, the tree should get selected by default

Occurring with:
2018.3.0a6 (13fac50c9eea) , 2018.3.0a5, 2018.3.0a4

Note:
New Terrain tools are introduced from alpha 2018.3.0a4. The same functionality was working with 2018.2.0f2

Environment:
Windows and Mac