In my experience, ATF field agents are very helpful in recovering stolen NFA items. (Certainly machine guns, although I'm not so sure about suppressors.) So it would behoove you to report such an event to them right away.
This happened to someone who bought a machine gun from me many years ago. He got the gun back (a watercooled belt-fed Browning), but not some of the stolen accessories.
BTW, the weak link in security is while the item is being transported. This fellow had the gun stolen from the trunk of his car.