I believe this is the best answer:

"I'm sorry to hear you've recently not experienced the product at its best. Right now we're rolling out a new algorithm in some of our courses and it’s exposed some shortcomings which we’re already in the process of fixing. Essentially, the algorithm should adapt to your personal memory strength quicker than it currently does. This means correctly answered words come back a lot sooner than before, resulting in not seeing new words for a long time. Since we’re rolling out the new algorithm course by course, it’s not been applied to Russian or Spanish, which explains the differences you’ve noticed.

This issue can be more frustrating for those with better memorisation abilities. If you find that’s the case for you, until the issue is fixed I’d recommend checking out our new challenges area which is full of speaking, reading and listening exercises."

source: Not getting new words in German course + repeat stack stuck at 0

@Il-ya-Tomberg

• Do you have any thoughts on this matter?
• It's a matter of principle
• It's just a matter of opinion
• We combined our forces to investigate the matter
• We did not dare pursue the matter further
• We need to examine the facts of the matter very closely

@Keith-Winston @Ash-Newton this was written on one of the updates, Dec. 4, 2017 (v2.16.18

What's New

• Work on your speaking skills in our brand new Challenges area! At the moment it’s available if you’re learning English or Spanish, we’ll be adding more exercise to more languages over the coming months.
• Some stability and reliability updates to keep Lingvist running like clockwork.

@Ig-Or You are right, you won't see all the available words/sentences because the Lingvist algorithm 'adapts' to our language level and trains us accordingly. I already wrote about the same 'issue'. So you are not alone.

"Supposedly the English course has 5013 words/sentences, but as far as I understand the Lingvist algorithm 'adapts' to our language level and trains us accordingly. In other words, we will see just some words/sentences from the big pool available."

source: Scratching the surface

@chiu1551

Desktop:

• Arrow - Top: will show the translation of the sentence

Android:

• On top of the card there is an arrow: will show the translation of the sentence

@Olivier-Ma-Dongqiang There are some keys that you can use to navigate:

• Arrow - Top: will show the translation of the sentence.
• Arrow - Left: go back (sometimes you have to press it several times to work).
• Arrow - Right: go forward.
• Enter: show the answer.

After you have completed the sentence, and click once on the speaker icon, you can use:

• Enter: to repeat the audio of the entire sentence as many times as you wish.

@Leonardo-Makoto-Kawahara @Juan-Pazos There are some reports of the bug coming back after some sentences, you can read at the end of the following thread:

• Stuck in the same place [Deutsch]

Furthermore, I've detected a small repetition under the sequence:

• 1, 2, 3, 1, 2, 3, 4, 5, 6, 4, 5, 6, 7, 8, 9, ...

where each number represents a different sentence. But maybe it is part of the 'new' algorithm.

I'll be testing it and will report back

You are not alone:

• Keep getting the same cards
• Algorithm falling apart

Usually the material for TOEFL, IELTS, and TOEIC is in English (I've seen some material in Japanese, but probably because of the difference in characters).

And when you start learning English you usually watch movies/shows with subtitles on your own language, then with English subtitles, and finally without subtitles. So it is part of a process, however - in my case - English movies/shows with English subtitles were a fast way to associate sounds to written words.

Lucky you!

Could you describe exactly what did you do between the moment you encountered the problem and got out of the loop?

Please!

Currently there are some other accounts affected:

• Keep getting the same cards
• Algorithm falling apart