Colorado says my e-file package did not include a certain form, even though that form is shown as having been completed. How can I see exactly what TurboTax filed?

To access your current or prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/

Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show.  Click on the Year and Click on Download/print return (PDF)

What form do they say is missing?

What edition of TurboTax Online are you using (Deluxe, Premier, etc.)?