Since the latest update (2.1.19) when doing a lesson it will “forget” progress on some of my words. What I mean is if I am doing 10 words per lesson, I will finish a block making half progress on all of them, but when I continue the next lesson 3-4 of them will be reset, so I have to do those words over again.
Its not a huge deal (I’m still learning) but it ends up adding an extra lesson round to each level, which is kind of annoying.
Sounds like its similar to this Android bug: Progress lost when learning 10 words per session