Yes, SpaceX lofted Zuma properly into the agreed upon orbit, and then the satellite likely failed to separate from the payload adaptor provided by Northrop. The satellite should have had it's orbit decay without the satellite being able to finish adjusting it's orbit and would have burnt up.

However, it is a perfect cover story for a satellite the NRO doesn't want people to know about-but Zuma should have been trackable and nobody found it, unless NRO has some super space stealth