GPX comes in different flavours
This is not a bug report, but I hope the info can be useful for the people working on the import module for Guitar Pro.
I have both GP6 and GP7 installed on my computer. Because importing the new GP-files is not possible yet, I tried to import several GPX files created with GP7. None of the imports was successful. Musescore crashed or the created files were empty.
Opening the same GPX files in GP6 worked fine. When I saved the files in GP6 the newly created GPX files could be imported in Musescore. But there some issues. The files have ottava like lines above all notes. The lines are not clickable and are no real ottava lines (on my 24 inch screen every line is about a cm long).
To remove the lines I saved the Musescore file as a MusicXML and reopened it. The end result is ok.