I have received this bug twice already.

If I were to disable my whispers and then log off without enabling them, when I log back on whoever whispers me can only find that my whispers are still disabled.

However, I have the ability to whisper anybody. When you disable your whispers it cancels out your ability to whisper anybody until you enable them.

And, when I do the command /silence to enable them it says "You will not receive any more whispers." making me have to do the /silence command twice to enable them again.

Can confirm this, experienced it the other night when logging off with silence.