Azir ult not being able to push back champions that start with certain letter.

so as a main of azir, i found this bug where he cant push back champion that starts with letter a or b with his ult. for example i found it not working: akali, ahri and braum. it wasnt happening before the latest patch, 4.19. they however are not able to pass through the wall which means ONLY push back isnt working.