External monitor not sleeping?

[robvas]

Hello, I'm using a 2015 Macbook 15" with the Apple USB-C to HDMI adapter (yes I have installed the firmware update on the dongle and am using the latest macOS), and when I put my MacBook to sleep, the monitor stayed powered on and will flash white every couple minutes. Very odd.

Same monitor connected with the same cable to my 2013 13" MacBook Pro doesn't have this issue - the monitor sleeps as expected.

Otherwise it works fine - just annoying to have to manually tun the monitor off and on when I use the MacBook. It's an Acer 21" LCD I bought a couple years ago at Best Buy.

Anyone else have this issue?

 

[deuxani]

I also had this problem with my Dell monitor. The way I solved it was by putting the MacBook in clamshell mode. When I leave the laptop open the issue occurs whenever it goes to sleep, but in clamshell mode the external monitor will go to sleep and not wake up until you use your mouse or keyboard.