The first command reports “All OK”, but test.7z is not created.
The second command reports an error, but the error message isn’t helpful at all. VSS doesn’t help anything if a program fails to write to a file. It’s for reading locked files… And the problematic file isn’t mentioned at all. By the way, there’s a typo, it should be “open”, not “opet”.
Only the third command (without ".\ ") works as expected.

The problem exists in the x86 and x64 version, it doesn’t matter if the archive already exists (updating) or not (creating a new archive).