Under 'settings' I see that I can enable infinite scroll on the homepage, but I'd like to enable it on different category pages as well. Can you tell me how that's possible? How I have my blog posts under one category but it also shows a dozen or so.
I'm not sure if I understand your question correctly.
To enable grid layout for specific category you just need to select that category from in Theme Settings: http://prntscr.com/e5u4l7
Infinite scroll is automatically applied to grid layout pages.
Unfortunately my infinite scroll for other categories is not working. If I go here for example: http://onceuponabrand.co/articles/ , it only loads the latest 8 articles.
that's because there as a JS error on that page, which is preventing any further JS actions to be done.
I can't see what is causing it because you have set JS to minify in your caching plugin (maybe even minifying it's causing it). I suggest that you disable JS minify and if that doesn't help then deactivate 3rd party plugins.
If you still can't debug, I could take a look of course but I would also need your WP login credentials.
That worked! Thank you!!