Quick search cyrillic text broken in last update?

Several days ago I updated Dopus FROM 12.Х (minor update).
I have filename "Обработка.ирПлатформа.Команда.СохранитьНастройкиПользователя.МодульКоманды.txt" in my lister with quick search field. Before Dopus update I typed "Платформа" in quick search field and it found my file. After Dopus update it gives empty list. "Find in list" and "Find files" both work OK.

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Does the same search match if you try it in File Explorer?

It may be a Windows Search issue rather than an Opus one.

Yes. The same problem in File Explorer. Most long search values give (false) empty results.
This folder contains 5000+ files. I think such big number is somehow involved.