Keyboard not showing up in specific case

REPRODUCIBILITY (% or how often): 100 %
BUILD ID = OS VERSION (Settings > About product): 4.0.1.48
HARDWARE (XA2, Xperia 10…): XA2
UI LANGUAGE: Norsk
REGRESSION: (compared to previous public release: Yes, No, ?): Yes

DESCRIPTION:

When trying to enter some text in Duolingo app, the keyboard is showing up only for less than a second and cannot be launched for any longer.
Example screenshot: https://ibb.co/QX1k2d7
The same issue occurs in Duolingo when there are two text boxes to fill in. In general, for one small field the keyboard appears normally. In my case, Spanish course was taken (may be important, as the courses differ from each other significantly and may not be reproducible for others).

PRECONDITIONS:

Sailfish OS 4.0.1.48, Android Support, Duolingo

STEPS TO REPRODUCE:

EXPECTED RESULT:

Keyboard shows up when tapping text input box

ACTUAL RESULT:

Keyboard appears for a while and disappears

ADDITIONAL INFORMATION:

(Please ALWAYS attach relevant data such as logs, screenshots, etc…)