Part name lost

If I edit the attached score, bring up the Parts editor, press New, change the Part title to "Soprano", select the instrument "Soprano Saxophone", press the [+] button, then press [OK]

A part gets created named "Part". It has the notes from the soprano saxophone, but the words "Soprano saxophone" don't appear anywhere in the score.

This does not depend on the score I attached. It is reproducible from a blank score.
1) edit instruments to add a piano and flute
2) edit parts and press new
3) edit the part name in the popup form changing "Part" to "Flute"
4) Select the Flute instrument in the list of instruments
5) press the [+] key on the form
6) press the [OK] key on the form.
You'll see that a part is added named "Part". If you take a look at the part you'll see that the Flute label is missing.