Text added to frames after generating parts not linked to parts

since "join scores" does not exist in Musescore 3, I had to compile the different movements of an orchestra suite the old way: "add section", copy-paste and "add vertical frame" for the title. Now I want to export the parts but all the titles -except for the fist one- are gone, just an empty frame.

Steps:

1. Write music and produce parts
2. add a title at some point