Download bookmarked articles to read offline

I have been using KA for a few years now and it’s great! More recently I use the app on my tablet so whenever I am away from home, I can learn some electrical engineering. My problem is the flights in between. The download bookmark option seems an obvious choice: Download a module, watch the videos, simple! But when you want to read the articles in that same module you just downloaded, you get a message saying “Could not load this article”. Clearly the download feature works for the videos but not the articles. My question is WHY? This makes no sense; surely the videos take up all the data.