When Mapping Objects "*** Error: NDS object "NDS://Server/O=Org/OU=Users/CN=User1" not added to the database because it is outside the OU currently being migrated." appear in the log file.
There are objects that are members of other objects outside of the current mapping area. This could be a user that is in a Different Organization or Organizational Unit that is a member of a group in the current objects selection.
Look at the error and identify if you need the object. Map those objects separately and then to make sure they get entered into their respective groups, re-synchronize the groups.