Firestick 4k Max - No UHD on Vudu

Hey all - I just bought the new Firestick 4k Max, when I try to view UHD/4K movies I have purchased on Vudu, the only option I get is HDX. I have tried restarting the device and changed the display settings, but the Vudu app doesn’t give me an option for UHD. Does anyone have any suggestions? Thanks in advance!