This is so weird. I have a few of the 10TB and 12TB WD EasyStores. I've been using them regularly for years and have never experienced anything like this.

Just to be clear, the drive does go to sleep when it's actually idle. Not while it's being used, though. IOW, they work as expected.

What distro/kernel version are you on? I mostly use Debian stable, which means a pretty old kernel. I wonder if it could be a regression in more recent ones?

I also use the drives with FreeBSD and have never had an issue there, either.