Duolingo Bug : cannot open "listening" exercise

Описание: I've experienced this bug a couple of times lately. I open the Duolingo app, and try to click on one of the exercises with the headphone symbol on its button.

A widget appears that is supposed to allow me to "review" the exercise, but clicking the "review" button on this widget does not work.

There's a quick flash as the screen goes blank, and then I see the home screen again.

This is not a networking bug, so far as I can tell. When it happens, I can still do other types of exercises.
I just checked the version number: I'm at 6.55.3. When I tried clicking on the "review" button just now, I saw a quick message appear at the bottom of the screen:
"An error occurred. Try again later."
That error message didn't show up in the original screen recording.