NSFW and Spoiler setting not respected on feed

Browsing my feed, which contains both NSFW and Spoiler-tagged posts, there are NSFW/Spoiler posts with the header image (NSFW or Spoiler) correctly showing, but then the first few lines of the post are still displayed, as if they were regular posts. I'm thinking this is not expected behavior. (And also I am slightly annoyed at being spoiled. Boo.)

I'm running the Imzy app on iOS 9.3.5 on an iPhone 5S; I can provide screenshots if you want them.