Can't strengthen skills

[liscio11]

For some reason, I have been unable to use the "strengthen skills" button for several days in a row- it tells me that all my skills are strong, and I should do a new lesson or translate. However, my skills are starting to deplete on some lessons already, and I see under words that I have many words that need practice. I'd really like to keep reviewing while I move forward rather than having to just keep forging on! Anyone know what I can do to fix this?

[facedancer]

I have the same problem with “Strengthen skills” for over a week! I have finished my German tree and now have 22 topics that need revising AND words I haven't practiced for over a month, and still Strengthen skills doesn't work (nor does the dumbbell button in the app).

[MiroslavFris]

This is quite known problem and I can also see it as a very annoying defect. We can only hope that duolingo developpers will want to improve this....