What’s keeping my M1 Max MacBook Pro from sleeping with the lid closed?

[DominikHoffmann]

When I put my M1 Max MacBook Pro into my laptop bag in the afternoon and pulled it back out mid-evening it was very warm, and the fans were running like crazy. It evidently did not go to sleep, and the fans tried to keep the system cool. It was about 110° F. If it were my kid’s forehead, I’d say he’s got a high fever. The battery was drained pretty well, too.

What could possibly have kept it from going to sleep?

 

[SierraVista]

Most of the time this has to do with some background process getting temporarily stuck and a reboot is enough to resolve it.

If not, or if you want to see more info, you can look at the power management log in the Terminal: https://apple.stackexchange.com/a/437659

 

[PotentPeas]

Apps can request that the system not sleep if they are running some kind of background job. For example, I've noticed that Lightroom Classic is guilty of keeping the system awake sometimes. (When it is behaving this way, the screen won't even turn off if I lock the system.) You can look in the logs, or otherwise it is sort of trial and error to figure it out...

 

[Ray2]

Could also be the lid. My M1 Air could not be transported without a 3/4” rubber band wrapped around it. The slightest movement of the lid would wake it.