Yes, but I've never seen it not show partitions that Windows itself created. Anyway, that's why I suggested the OP use a third-party utility that tells him the exact partition type ID. Why even depend on PS - which is still a Windows feature - to analyze this unknown partition? No wonder the OP has to keep repeating what he wrote:
Mine used to be displayed as drive H only when I checked the 'Show hidden items'. It's no longer appearing after the Anniversary Update too. With the recommended command by 100 I can still see it at the shell command prompt.
I agreed with 100’s assessment that it was the ESP, because I did what he suggested, namely I ran "mountvol" in a command prompt, and got exactly what he said, namely the line “The EFI System Partition is mounted at Z:" Btw, I’ve just tried running the command again, and that line and the letter Z have now disappeared, as did partition Z in FE. Disc Management continues to show what it did before. There’s thus no point in running any utility, as there’s no (partition) Z for it to find. Since other users also reported on the web seeing partition Z and nobody knew what it was, my uninformed guess is that its appearance was due to some glitch (small bug) of the system that was put right by the last update. The post above by H-D seems to add strength to this guess.
True, but this is an OEM preinstall. Who knows what they were thinking. Why not? Are you expecting the Windows storage API to lie about the partition table? Just because there's no drive letter assigned (or disk management not showing the partition) doesn't mean the partition isn't there.
[ I never said it isn’t there. On the contrary, it must be there, otherwise the system wouldn’t boot. But we know it’s there, so what’s the point of verifying it’s there? What I meant of course, and I said it clearly, is that there’s no letter Z to associate with anything and investigate the original question further. And besides, that question has been answered anyway, and by your good self to boot (no pun intended), so we can give the matter the boot (this one was intended).
No, not about stuff it knows about, but if I was investigating an unknown partition I'd definitely employ better (Linux-based) tools. Anyway it looks like we can lay this thread to rest now.
I read the whole thread and still didn't get why OP got ESP visible as drive Z Can someone explain me this? What made it appear visible?