Software RAID Windows 10
It is not surprising that Microsoft has lowered support for software RAID, as since Windows 8 it has incorporated a more advanced RAID technology that is called Storage Spaces. Microsoft always phases-out older technology in favor of newer one. If you really want the classic RAID, you'll need the Pro or Enterprise editions of Windows 10.
Storage Spaces are volumes rendered upon spanned pools utilizing multiple drives, in effect the same as RAID, just much easier to set up.
Here are a couple of references from the thousands that you can find on the Web:
- How to Use Windows 8 or 10’s Storage Spaces to Mirror & Combine Drives
- Windows Storage Spaces and ReFS: Is it time to ditch RAID for good?
If you are multi-booting Windows 10 and Windows 7, beware - Windows 7 will not understand Storage Spaces.
Ability to add a mirror may only exist on Windows 10 Pro and Higher versions. I noticed you were using Home in all versions shown.
Looking for that option in Windows 10 Pro, I was able to select the "New Mirrored Volume" option.
There seems to be multiple other users noting this behavior on Microsoft's forums. https://social.technet.microsoft.com/Forums/en-US/becca8a4-14c1-4341-9bb7-4730079819a3/i-dont-have-add-mirror-option-in-disk-management-in-windows-10?forum=w8itprogeneral