Both Airbus and Boeing have what they call undisclosed orders. Basically a deal with an airline for orders. Since the airline and manufacturer can’t agree to final terms; neither wants to make the announcement. When announcements are made; that usually is because the final agreement is very close. Or it is done and both parties just need to sign the document.

Even after the order is placed, Airlines can cancel, defer or even sell the plane to another. Unless you see it on the ramp, it can all fall apart.