ChromeOS, where sleep presumably worked, is also Linux. You just exchanged a working Linux for a distro with more bugs. The fact that you're able to do that is pretty cool.
That's not to detract from the larger point here though. It's pretty funny that all of the replies in this thread identify different causes and suggest different fixes for the same symptom. Matches my experience learning Linux very well.
Big fan of Linux, but saying that Linux works on system76 while they have a tiny sliver of the Linux market share seems like a nonstarter.