Usually, with ctrl+shift+u the "find usages" function is started. However, since recently this does not work anymore. Instead, "ctrl+shift+u" just enters a small "u" into the editor.

In the settings (Environment->keyboard), Ctrl+Shift+U is set as keyboard shortcut for find usages. When trying to change it and hitting "Ctrl+Shift+U" to set it to a new shortcut, also a small "u" is entered. Other combinations like "Ctrl+Shift+G" arre correctly recognized as "Ctrl+Shift+G".