Bug: one of my courses disappeared

One of my courses just disappeared today. I can’t see it anymore in the box “Continue studying” when it is set to “Courses”.

It’s a book I imported myself (first Harry Potter book in Japanese) and set to private. Last time I used it was yesterday. Of course I already checked the filters (e.g. it is set to Beginners 1 to Advanced 2). And I clicked on “View all” Even the search doesn’t find it.

If I switch the box from “Courses” to “Lessons” I still can see the chapters of the book. So it wasn’t deleted.

Please fix this bug.

To help narrow it down: the book is in Japanese so a lot of data is in kana and kanji and doesn’t contain latin characters. The book was there every day for over a year. It just disappeared today, yesterday I still could access it. It didn’t change anything to the book/course besides reading it. Tried to access it on iPad, iPhone, Win10+Firefox. Same problem on all three platforms. My timezone is CEST/GMT+2.

Update:

Now the course is back if I go to “view all”.

While I had the problem the website (not the apps) also was extremely slow and pages sometimes didn’t load at all. Maybe it was a side effect of that.

I’m pretty sure it’s a bug as the same thing happens to me sometimes (continue studying has the lessons but not the course).

If you notice the same problem again, please email support and let me know what’s the course title. Thanks.