applications – The "Offline Dictionaries" application keeps losing the installed dictionary

I am using the Offline Dictionaries application on Android 8.1.0, on a Redmi 6 smartphone (global version). I have installed a single dictionary, "English (Wiktionary)", which is installed in / storage / emulated / 0 / DictionariesNGHS.

Frequently, when I open the application, it says "there are no dictionaries installed", and I need to reinstall the Wiktionary in English again (it has about 22.6 MB). Why is this happening and what can I do to solve it?