URLs for your site and alternate URLs in 'x-default' that do not have return tags. / --> http://example.com/en/

This means that http://example.com/en/ doesn't have doesn't have x-default to http://example.com/

URLs for your site and alternate URLs in 'pt' that do not have return tags. / --> http://example.com/ptb/

http://example.com/ptb/ doesn't point to http://example.com/ with x-default

URLs for your site and alternate URLs in 'it' that do not have return tags. / --> http://example.com/it/

http://example.com/it/ doesn't point to http://example.com/ with x-default

Basically, you need to have absolutely the same hreflang alternate tags all over your website; on every language absolutely the same tags.

URLs for your site and alternate URLs in 'x-default' that do not have return tags. / --> http://example.com/en/

This means that http://example.com/en/ doesn't have x-default to http://example.com/

URLs for your site and alternate URLs in 'pt' that do not have return tags. / --> http://example.com/ptb/

http://example.com/ptb/ doesn't point to http://example.com/ with x-default

URLs for your site and alternate URLs in 'it' that do not have return tags. / --> http://example.com/it/

http://example.com/it/ doesn't point to http://example.com/ with x-default

Basically, you need to have absolutely the same hreflang alternate tags all over your website; on every language absolutely the same tags.