Apparent discrepancy between check and build_manual

I have built the manuals for a number of packages (e.g. with both devtools::check that includes manual = TRUE and devtools::build_manual.

I have found that, when using build_manual, the Author and Maintainer fields from DESCRIPTION are not included in the manual preamble. However, the information is included when check is used.

The manual in the vignettes subdirectory on the github site was built with build_manual and so does not include the information.

Is this a bug or a feature? Is there a workaround in which only the manual is built.

Thanks in advance for any help,