the case of the missing spell

[Scellanis]

It did, it was Avada Kedavra and the intended effect was to kill Harry...the actual effect was a bit messy and didn't result in the death of anyone either so maybe thats why it can't have a shadow.

I still think nothing came out of the wand because there was nothing definite in the spell's actual effect that could be turned into a shadow form and pushed out of the wand.