Save a part as a copy erases its name

2.1 version 871c8ce / Windows 10

1) "Untitled score"
2) Create parts -> New all -> Ok
3) View part
4) File -> Save a copy -> Save
5) Return in File -> Parts -> Hit "Ok"

First result: the part name is erased in score (tab)

6) Save score / Close/Reload

Second result: part name is erased too in File -> Parts
(NB: same result by exporting a part in .mscz format)

- First reported in: https://musescore.org/en/node/235636