USB keyboard typing freeze

Good day
I have a very annoying problem with typing using my keyboard. In each Qt application, which I use, like: Kate, Spyder, Telegram and even non-Qt based Sublime, after pressing a key combination with Ctrl key in one of 5 times the following input symbol after this combo will not be rendered on the screen. I have found a very simple test to reproduce a bug: select a full word from a sentence using a combo Ctrl+Shift+arrow_key and then press any symbol key. As I have said, in my case in one of five times the second keyboard key pressing is not effective and doesn’t overwrite the selected word as it should be. Only double or triple pressing produces a symbol on a screen.
For GTK applications, like gedit and Firefox, there are no problems with typing
Accessibility settings are disabled. I tried several advices related with GPU driver like UXA acceleration and disabling frame buffer compression without any success.
The only thing I haven’t tried yet is to disable xorg libinput driver and use evdev instead.
Seems that this thing is related only to usb keyboard both wireless and wired, but for my laptop embedded keyboard connected via PS/2 works good without any lag or freeze
As for my configuration: I have a fresh installation of Leap 42.2 running on core-i7 6700.

Thank you in advance

I have a more detailed example. With a word selected using Ctrl+Shift+arrow, and then pressing an “a” symbol produces nothing but then repeated pressing this key gives this å. If press “s” key it would produce “ß” and for f it is ''ff". Typing now this message, I’ve had two times when it was like auto-repeating input however I didn’t keep any key pressed to produce it intentionally.

I reproduced this bug on several different computers and with different keyboards. On one computer along with Leap 42.2 I have Mint 18 Sarah installed . Mint works perfectly without any glitches and lags.

Finally, I have found a solution.

Seems that a Ctrl_Right+Shift combination as a compose key retains in Qt applications and some others despite of system settings.

Such a relief.