get_header not bringing in pngs

Hello! Hope all of you are doing well.

Had a question that I don’t really understand what is happening.

My site is Hatched Prints, and I have a custom designed theme that I have uploaded and are using with wordpress. As you can see, the top bar on the home page has 4 little “circles” as just a design feature. However, if you click on any individual post, the circles will disappear.

In single.php I have a get_header function called out which should be bringing in the same header as it is called out on index.php the same way. I have even gone so far as to copy the header.php code for those 5 categories and 4 circles into the single.php file with no luck.

Am I missing something obvious?

Thanks!