p7zip, including the latest version, ignores the working directory parameter when creating a multi-volume archive with -v, e.g.
>7z a -w/tmp ~/achive.7z folder123
creates the creates the archive in /tmp and them moves it to the home directory
>7z a -w/tmp -v50m ~/achive.7z folder123
creates the archive in the home directory from the very start ignoring the "-w.tmp"