Nvidia has made us aware of an UHD issue that will affect Vudu Nvidia Shield users and prevent playback in UHD quality. Due to this, UHD playback on Nvidia Shield devices will be limited to HDX quality starting at 3pm PT today. Playback on other Vudu-enabled devices will not be affected, and you will be able to watch your collection in 4K UHD on non-Nvidia Shield devices.

We understand this is frustrating and inconvenient but rest assured that you will still have the UHD quality you purchased and will be able to watch in UHD when the issue is resolved.

You can find additional information and updates on the Nvidia forums, here.

In the meantime, you can always cast to the Shield in UHD quality, though you'll be missing HDR.