Apple TV goes black intermittently

My latest gen Apple TV is connected to a 1-year-old Denon receiver and a 4k TV with a high speed 8k-certified Monster Cable HDMI cable. During the first 30 minutes or so after the ATV is turned on, the image periodically goes black for 2-3 seconds. Audio remains unaffected. When it comes back, it usually shows the Dolby Vision logo in the upper right corner (determined by the content I assume). Since this only happens within the first half hour or so, I’m wondering if I have a buggy ATV. This never happens with any other input source.