Pink Wards not Revealing Stealth Wards.
I came a cross an issue yesterday where a pink ward I had placed immediately after an enemy had placed his stealth ward failed to reveal said stealth ward. I had to use my sweeper to clear it out.
The pink ward was at the top of the red-side bush over the wall from Blue buff, and the green ward had been dropped just over that wall, so it was most certainly in range. Just a heads up that the wards need a bit of work.