Seems odd one box works and the other does not. Normally I get an error message if there is an issue with any apps, normally Netflix and a reboot sorts it out. My main box is set up to 4K tv but supports hdcp 2.2 so not sure why there is a problem!
Same issue here for past 24 hours when trying to access BBC iPlayer via Catch Up. Attempts to load then a few secs of a black screen before it throws you out and back to the Channels screen of Catch Up. No problem accessing iPlayer via other devices. Impossible to get in contact with Virgin at present to flag up issue or get advice.