Marvin 3 CBZ CBR metadata problems

I have a large collection of comics that I want to import via calibre content server. However, when I try and import the comics, the metadata is messed up. For example, I have a file "Title.cbz" and author set in calibre.

When I try and import via calibre content server, I find the name messed up as "Title - Author_xx" and the author listed as unknown

I know that Marvin looks for metadata from within the epub files, however, I can't seem to find a way for Marvin to get the metadata correct for cbz/cbr files. When I import these files into my eraeder, the metadata is read correctly. Is there a way to import these files correctly into Marvin?

Thanks for any pointers.