child theme for specific webcomic not importing child css

[ThomasDotCodes]

I've setup a fresh install of WP 3.9.1 with the webcomic.nu plugin, along with the inkblot-master theme, and an 'inkblot-child' theme which has the same style.css from master (but with a modified header), and I've also copied the custom.css file.

If I load the inkblot-child as my main WP theme, it loads the custom fine. However if I set "inkblot-master" as my main WP theme, then set the specific comic theme to "inkblot-child" it doesn't import the custom.css

Am I missing something?