In a personal course I created, I deleted two levels and created new ones in their place - however, though the levels are gone on desktop, they remain on the iPhone app, and some words from those levels show up among randomized answer choices when I study other levels. (The “ghost levels” that should have been deleted are “10 - Prefectures/Capitals 1” and “11 - Prefectures/Capitals 2”.)
However, since this started happening I’ve added new levels on desktop - and those levels show up fine on iPhone, and any edits are synchronized immediately. So essentially it’s that one glitch.
I just want to say that I’m having exactly the same problem. I deleted ~4 levels from one of my courses, but they still show up on the iOS app. Everything else works fine, though - all new levels/words synch up with the website, as do other edits.
EDIT: I deleted the app and reinstalled it, the ‘ghost levels’ have disappeared and everything’s back to normal.
Sometimes the changes might not kick in automatically.
What you can do is try to rearrange the level order of the course (move level 2 position to level 1 or vice versa and then back to original) or add then delete a word in the course.
This will cause the course to automatically update and should fix the issue.