Google Webmaster error "Missing: Author"

I know people have asked this before but I went through all of the previous answers and still have not found a solution for this problem. Google Webmaster tools indicates that 128 of my posts, pages, and products are missing author information. I’m not sure why this is, since I am the only author on my site and they all show my name as the author in my dashboard. I’m trying to optimize my SEO so I’m checking everything; if this doesn’t affect my SEO then I’m not worried about it

I’ve found a lot of information about php code, but they were written before the latest theme update and it appears some things have moved around. Is it possible to fix the problem in CSS? If not, please let me know exactly which php file and line I need to edit in my child theme.

The site is https://www.joe-the-baker.com and some of the errors listed are as follows:

/blog/
10
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author

/category/cookies/
10
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author

/category/cakes/
10
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author

/tag/french-macarons/
9
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author
Missing: author

/category/pate-a-choux/
4
Missing: author
Missing: author
Missing: author
Missing: author