I am not convinced that this issue is to do with High Sierra. I am also experiencing this problem and my computer is on El Capitan. I mentioned this in my post from a couple weeks ago. I have a 2015 MacBook Pro. It is not now nor has it ever been on High Sierra. It didn't have this problem when I originally got it, but started having it after a certain point in time, though I can't remember exactly when that was. I believe something else might be at issue.
If possible, it would be nice to see if anyone could downgrade from High Sierra to Sierra or to Yosemite and observe if the problem remains. (Some people mentioned downgrading to Sierra, but I didn't see them mention if that fixed the problem or not, but then again, I did skim most of the posts here, so maybe it did.) If so, we could then conclude it's not an issue with High Sierra at all, but rather something else and then see if there is any other pattern that might point us in the right direction such as it happens on computers from 2012 and later while 2011 and earlier models (even those on High Sierra) are not having the issue (that I have seen reported anyway).
Now, here's why I say if there is a pattern of 2012 and later models having this issue, this would be useful information. 2012 and later models of Macs had a change made to the type of graphics API that they use. If on any Mac from 2012 and later, you will be able to make use of the Metal graphics API. However, if you have a 2011 or earlier Mac, you will be stuck with the OpenGL API no matter what OS version you upgrade to. 2012 Macs did not originally use the Metal API either (nor did 2013 and maybe 2014, iirc, but don't quote me on that), but these Macs could still obtain and use it by upgrading to El Capitan (or anything after it). It's possible that if you had a 2012 or 2013 or so on Mac that you had, say, Yosemite and then upgraded from it directly to Sierra or High Sierra, skipping El Capitan, but nonetheless going from using the OpenGL API in Yosemite to Metal and there your problems began. (I did see a person or two mention they were on Sierra and never had this problem until High Sierra, but they might be anomalies. Others mentioned doing things that fixed their problem that nonetheless didn't help other people, i.e. turning off WiFi (I tried this and it didn't work) or changing power nap settings. They might also be anomalies. Or they might have actually started seeing the problem again. Who knows. They haven't reported back.)
Given that my 2015 MacBook Pro on El Capitan is having this problem and given that I have seen no mention in this thread of any Macs older than 2012 having this issue (though I admittedly skimmed through the many pages of this thread, so speak up if you have a 2011 model that is having this problem and I missed it) I think it's not unreasonable to conclude that the problem might actually be related to the graphics API rather than anything in the OS version. Also, many people have said they upgraded to High Sierra but didn't mention what they upgraded from nor the model of Mac they have, which leaves the possibility open that they're on an older Mac (like 2012 that didn't ship using Metal) and upgraded directly from, say, Yosemite, to High Sierra where their issues began to happen (though I suspect it might have started happening if they upgraded to anything from 10.11 onwards as well if my suspicions about the graphics API are correct).
My knowledge of graphics APIs and how they function is rather limited, so I am not sure how they could or whether it's even possible that they could cause problems with sleep/wake, but on the other hand, I have encountered problems that were caused by things that didn't seem at all related, so I wouldn't necessarily eliminate it as a possibility.
If not the graphics API, then I suspect it might be something else that was introduced in some OS upgrade at some point that 2011 models and earlier cannot make any use of and so do not have it. It has to be something that was introduced with El Capitan since, as I've mentioned, my 2015 MacBook Pro is on El Capitan and is having this problem as well. I point out the graphics API, though, because it is the one thing that I know separates 2011 and earlier Macs from 2012 and later ones. Again, no 2011 Macs are mentioned in this thread, so it seems to coincide.
My 2011 MacBook Pro, it should be noted, which is using the same OS as my 2015 one, is not having this problem. I don't want to upgrade that one for specific reasons, but for testing purposes, perhaps I could upgrade it and report back on whether it starts having problems. I am fairly confident, if I am right about Metal, that it won't. If anyone in this thread has a 2011 Mac on 10.13 or later and is having this problem, let us know. That will debunk my theory but at least help eliminate it as a possibility.
As a parting statement, I will say that I make no absolute conclusions about Metal being the problem. There were, as I mentioned, some posts that seem to already contradict my theory, but I also don't think I have enough details regardless to throw it out. Since not all Metal Macs have this issue (or we'd be seeing many, many more posts about this, I'd surmise), I'm not certain it's the cause at all, but I do think it could still be related. I think, for example, it could be something to do with it plus something else that these computers all have in common, that that combination is what causes it. Maybe it's the type of graphics cards all these computers are using plus Metal. Maybe it's a program or something else all these computers have in common plus Metal. Maybe there was a change made to Metal that happened to coincide with the release of 10.13 that nonetheless affected other versions of macOS (which would explain my El Capitan Mac having this problem and only seeming to have it after a certain point in time, though I can't say when that was exactly, and why people didn't see this issue on Sierra but did on upgrading to High Sierra (when did you upgrade? As soon as 10.13 was released or not until many months later?). Who knows? I just find it suspicious that 2011 Macs don't seem to be having this problem, but anything after 2012 is regardless of being on High Sierra or not (like my 2015 MacBook Pro on El Capitan). The only thing that is different between 2011 and earlier Macs and 2012 and later is their ability to make use of Metal, though I think there was also a change with Airdrop that affected 2012 and later models that 2011 and earlier can't make use of that might also coincide here as well (someone's mention of messing with WiFi fixing the problem for them seems to support that, but others' mentions of it NOT fixing the problem contradicts it).
Sorry for rambling, just trying to see if I can pinpoint the problem since it's become so prevalent and disruptive for a lot of people (including myself).
