I am also having this issue too, where the header settings change on the blog post page to white (as opposed to matching the heading settings set globally which in this case is a navy overlay with all logo and nav links in white. Hence they disappear with this issue.
https://www.sorayaking.com/blog
Does anyone know the code to correct this? I tried to work it out myself based on my fairly limited coding knowledge but am at a loss. It should match the below example as that is what is set globally...