Marked as won't fix, not a priority.
No selection highlight in ES2. Expected to be able to see what user has selected. Reproduced on windows and mac.
1. Open UE4Editor.exe QAGame
2. Set Preview Rendering Level > Mobile/HTML5
3. Select the floor asset
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-6458 in the post.