We are using SCCM 2012 R2 to deploy software updates.
On Windows 8.1 SCCM does not show certain updates as being needed and isn't deploying them to the clients even though Windows Update will show them as high importance. These same updates are being detected and deployed to Windows 8 clients successfully.
I believe that the update catalog that WSUS uses may have some incorrect detection rules for the following updates:
My automatic deployment rules include Windows 8.1 in the product category. I have even created a standalone rule for Windows 8.1 that builds a new package and the behavior is the same.
We only have a handful of Windows 8+ clients so this hasn't been a big issue but others may want to keep an eye out.