Haven't seen this question asked in recent years in the knowledge base: what does it mean if your X1 box needs to be manually rebooted almost daily? There is a message to check the HDMI connection, but everything is fine once the box is reset. Box is fairly new, installed in recent months. Connections are fine. Sometimes the box will blink nonstop for a day or two. Bad box?
Are you just restarting the box or are you doing a 'system refresh' from online troubleshooting? Try the latter from your account login or the xfinity account app if you haven't.
Also, I think there can be problems with HDMI handshaking when the X1 box is allowed to sleep and wakes up. You could try turning the power saver off in the device settings to see if it helps. If neither of those helps it is probably a bad box.