There's a max size limit of 1296pt.
Convert to outlines and scale as needed.
I think there's a way to keep this live and use Transform, but someone else is going to have to help you with that...
Someone else suggests to make it a symbol and scale the symbol instance.
... or apply the transform effect without making a symbol first
But only inside the appearance panel - I remembered!
The appearance panel should be at hand anyway, so I can't see why that should be an issue.
Should - it's a teachable moment...