Thanks, @garyopela for such a detailed explanation. 
I did try this, but the variable editor is still not visible on workspace. 

The odd thing is, if I add the same variable editor in Core UI and workspace, the variable editor vanishes from Core UI as well. 

If I remove it from the workspace view, it works fine in core UI. 

But, still no variable editor on the workspace 😞

Thanks,

Poorva