OK, it is happening again. I just created a new account, via firefox, and now the icons are not showing again. Seems, to only happen to logged-in users with WordPress administration privileges... I think...
For this: http://prntscr.com/vf9g5z
can you please share a video/screen recording for the same?
So I can ask my teammates to have a look(in case, I am not able to solve)
Atleast with that recording they were able to understand better