Lessons refusing to open

I’ve imported a long text which has been automatically split into 12 lessons. Lessons 2 and 7 are showing as having 0 new words and are refusing to open. Instead, I get this message: “There was an error opening this lesson. We have been notified and will investigate this issue. You will be redirected to the home page where you can try opening another lesson.” What does this mean? Clearly I don’t want another lesson - I’m trying to read a book. I deleted the course and reimported the whole thing and the same problem recurred. What’s the solution, please? Thanks.

I had the same issue as you. I thought it had something to do with audio but I guess not.

Please send me an URL of that course to support(at)lingq.com. Thanks!