Yes only connected to DVB broadcasts (in HD) and not with any HDMI connected devices (Blu Ray) or when streaming Youtube etc
Only affects the Connect UHD (both purchase new 2017) and seems prevalent when switched first switched on for the day; for example this morning I have just switched it on and the image went blank 4 times in 2 minutes then remains steady. When I switched it off and on again the fault didn't present itself which makes me wonder if its linked to updating overnight as I noticed the blue light illuminated at 2am; who knows
Here in the UK we have had ongoing issues with HD reception and Loewe TV's for many years. I had a Individual Slim which had to be returned for a refund as it was unusable in HD, exhibiting the same fault but constantly every few minutes, however things seem a lot better these days I must admit
Other than this glitch everything works perfectly and I can live with it for now so long as it doesn't get worse