I Export the XML From Gantt and then Import that file into Primeavera, not imported in Primeavera
As far as I know, there is no way to import Primavera files into Gantt.
The dev team will add that functionality in the future, but I cannot give you any ETA.
I didn’t test how to import files into Primavera, but did you do it the same way as suggested in the following video?
The dev team added support to import and export to Primavera: