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KDE's Applications Launcher Menu incorrect behavior

I noticed an incorrect behavior of the KDE's Applications Launcher
Menu in Debian: not all characters are printed when i type something
in search field.
For example, I type "kate", but "kte" has printed.
Sometimes only first symbol has printed.
The same behavior is in Discover application.
In other applications all works correctly.
It began when I have started to use standard system keyboard layouts
instead of IBus.
What should I do to collect more details of the incorrect behavior to
help to fix it?

P.S.: Debian 9 AMD64 KDE.