Exporting part scores

(Skip to paragraph two if you don't need an explanation)
My primary use of Musescore is to create orchestral scores and corresponding parts as high quality and as readable as possible. This requires making part scores that are different than the displayed parts in the conductor's copy. For example, a flute line in the conductor's score would have two parts, flute I and flute II, whereas the respective part scores would only have one line for the given part. This would require deleting certain elements or notes from the parts, which would in turn alter the conductor's score and the other parts which share the same line.

In previous versions, I could create all the parts from the dialogue, no problem, and then export them all as separate Musescore files (.mscz) and edit them without fear of it messing with the conductor's score. In Musescore 4, however, I can't export to .mscz files from the parts dialogue box. I have tried to export to MusicXML and open it in Musescore again, but that gets rid of some elements and alters some others. Is there any way of exporting the parts to seperate files, or do I just have to create new ones manually?

The current score I'm working on is attached if you would like to try your hand at it or if it's useful at all. Thanks!