i downloaded the 7z package v9.22 and used the older 7z.dll with your test project but the file name if still empty:

Name:  Screenshot - 04.02.2019 , 15_59_33.jpg
Views: 4697
Size:  35.9 KB

but with "extract" i can extract the tar file from inside the gz file with the correct filename!

any ideas whats wrong here?