2016 - 12" - clamshell mode issue

I use my mb as our family computer.

We keep in clamshell mode most of time.

Periodically (not always), when I wake up from sleep it's as if it thinks the laptop screen is up versus down.

I have to open the laptop to see the login screen.

I'm using Apples official AVAdapter with an HDMI monitor.

Any ideas ?

Thanks!