Only A,E,I,O,U keys working on Japanese Keyboard

in our qt5.15.0 build with the virtual keyboard, if you select Japanese input then only 'A', 'I', 'U', 'E', and 'O' are working.  When these letters are pressed, the correct Japanese character is displayed.  Any other character combinations do not work correctly - other letters display the english-text character instead of Japanese character