BIOS, missed a motherboard driver and security suites that block a write to the wait timer when it's a scheduled task.

I don't have much to add to priors but when I work this it's been cured about half the time and the other cure is to change the motherboard to one that works.

Not all PCs work in this respect so only those new to this issue think it's always a sofrware fix.

-> https://www.google.com/search?q=scheduled+task+does+not+wake+PC

Even Microsoft writes about it. I do not take well to anyone that write "This is just the standard canned response" as I do think about such and work issues like this. The awful truth is this is an area that might not work. And for most owners it doesn't matter so the makers drop the ball and hope no one notices.

https://support.microsoft.com/en-us/help/2586195/wake-the-computer-to-run-this-task-function-in-task-scheduler-may-not shows that the HARDWARE can have issues. Really messes with those that didn't know this.