ward placing bug when normal cast

I had experienced this bug at least ten times. It is pretty sad I don't have any pics or videos to prove it. If anyone had experienced the same thing as I did. Please comment!

So this bug is not that significant, but sometimes does a negative influence to gameplay. So I think when I am normal casting, if I place a ward , I press number 4 first, and then left click the position I want the ward to be at, then the champion would walk there and place the ward. This is what happening for most of the times. However, there is a bug happening sometimes, that the ward would be placed right away, but not the position I wanted. I had tried quick cast which I never met this bug. This sometimes would waste a ward, so should be fixed!

My English is not that good so I hope I explained the bug well!