So Sorry...
I just posted a pretty frustrated message, and then got the new 7zip just to verify to myself that it didn't make any difference.
However, it does work, but differently than any other previous versions of Toucan.
I can see where this MIGHT be the best way of making it work.
The backup filename is used to make a directory, and then the BaseFile that gets created is put INTO that new directory. 7zip beta handles this just fine. Earlier versions of 7zip want that directory to already exist.
I'm assuming that incremental/differential backups of the same job will go into the same directory.
Anyway, sorry for posting that frustrated message that is no longer there.
I'm not sure if you want to use a beta version of 7zip in your distribution. I haven't tried 4.57, but the one you were using is 4.41 (I think).
Jim