Trying to get the topic back on track
The way Channels DVR decides which channel to record from is based on a number of factors that have been endlessly talked about on the forum. As far as I know, it doesn't differentiate between UHD (4k) and HD. It might for a 4k HDHR tuner, but not sure. Since Fox and Fox Sports don't have dedicated 4k TVE channels (just certain events on the channels), Channels DVR doesn't use the fact an event is HD or UHD and instead goes by the TVE channel and assumes it's HD (like SD vs HD).
Also for those posting that don't know, read this Topic Fox @ 4k HDR Local Fox TVE in 4k starts here Fox @ 4k HDR - #231 by tmm1 . Fox TVE does have "some events" streamed in 4k, the next being FIFA Women's World Cup-France vs Brazil this Saturday morning.