Parcels created during parcel construction cannot have duplicate names, or they will be saved as unjoined parcels.
If parcels created during a construction have duplicate names, they will be saved as unjoined parcels.
Solution or Workaround
After building a parcel construction, do not name any of the parcels identically in the same construction.
If having the same name for more than one parcel is desired, then give the parcel a temporary name, save the construction, re-open the job, and rename the parcels individually.