Diana's (W) Pale Cascade Bug.

Hi, Today while playing , I noticed a bug (?) which is related with her (W) ability. While in a team fight (!!!) her W cooldown did not reset neither after exploding all the orbs - second shield appears normally. Cooldown refresh timer didn't go off, until the icon of the spell - above the interface- disappears. It happened 4 times when was in Team Fight.