I usually leave my computer, and let it go to sleep after 15 minutes.
My external screen is showing a blue screen saying "HDMI no signal" every other minute while my MacBook is asleep, and the screen lasts for a few seconds. If I unplug the external screen, the message appears for a longer period of time. It did not happen with other computers (I have tested with a MacBook Air and a Windows Surface PC). The built-in screen is turned off and does not blink in any way.
Setup: I have a MacBook (Retina, 12-inch, 2017) running MacOS Mojave (10.14.1). I have a USB-C Digital AV Multiport Adapter, to which my external monitor (ASUS VS248H) is connected using a HDMI cable.
Question: Is there any way to avoid screen blinking (except for turning the screen off when I leave it)? I.e. sending the correct signal to the external screen, so it does not think it is disconnected.