It's common knowledge that you can flash during the channel of a skillshot to cast it faster after.

Ex: Pulverize+Flash, Charm+Flash, Chain of Corruption+Flash.

So why can't you do this as Elise with her cocoon? There is a channel before the cast, but if you try to flash during that channel like almost every other ability with a channel, it won't work. You'll flash forwards and the cocoon will be fired from where you were before the flash.

I don't understand why she is not consistent with all the other abilities.

Edit: Please don't downvote, this is an honest question. Here is an example.