A user from Russia left a review stating, I want to share a workaround:

Что можно сказать о программе, в которой нельзя задать нужное тебе сочетание клавиш. Нажимаешь альт + кнопку и оно добавляет к этому контрл. Человеку видать времени не хватает оттестировать свое поделие и это должны делать за него пользователи.

(Translation: “What can you say about a program where you can’t set the desired key combination? You press Alt + a button, and it adds Ctrl to it. It seems the developer doesn’t have time to test their product, and users have to do it for them.”)

Unfortunately, the user did not leave any contact information, so I can’t respond directly to their Microsoft Store review.

After investigating, I found that on the Russian Keyboard Layout in Windows, the Right Alt key sends a signal as Ctrl + Alt, which Lookupper interprets as a combination. Regardless of the prompt in the settings, this binding with Right Alt should work. Unfortunately, if you switch to the English layout, it will not work because the English layout binds Right Alt and Left Alt to the same keyboard modifier code.

Solution:

1. Keep the keyboard layout set to English and use Alt keys interchangeably, or
2. Ensure that the Russian keyboard layout is active while using Lookupper, and use Right Alt as a modifier, regardless of the Ctrl + Alt binding.

I hope this helps anyone who encounters the same issue with keyboard layouts.