Windows 10 Update KB4517211 Breaks Cortana Search Functionality, Turns Off Windows Defender

Microsoft rolled out new Windows 10 cumulative updates for support versions of Windows 10. The tech giant specifically pushed KB4517211 for PCs running Windows 10 version 1903.
The update brings a handful of quality improvements and fixes a series of bugs in the OS. The changelog suggests that KB4517211 specifically addresses audio issues in different games. These issues were initially reported after the release of Windows 10 update KB4515384. There were multiple reports about low or abnormal sound in games.
Although this update patched various major issues for the users of Windows 10 May update, still many people started reporting various issues within a few hours of its release.
Installation Failures
We cannot deny the fact that Windows 10 users need to deal with installation issues with the release of every new update. It seems like KB4517211 is also affected by the same problem. Those who tried to install the update confirmed that the installation process fails at 20%.
Anyone else having this problem and discovered a workaround?
My several attempts at installing Windows 10 update KB4517211 ‘reliably’ and repeatedly fails at 20% – whether attempted from System Update or a direct download. Update Troubleshooter is no help.
Cortana Search Issues
There are multiple reports that the latest Windows 10 update KB4517211 breaks Cortana search feature. One of the users who experienced a similar problem explained in Microsoft’s Answers forum.
KB4517211 solved my issue causing the start menu into critical error.
However it still does not allow using the “cortana search box”, or searching for any app.
Anyone else having the same issue?
Windows Defender Scan Turned Off
Apparently this update introduced various new problems in the OS. According to the forum reports, the installation of this update automatically turned off Windows Defender virus scanning functionality.
After installing KB4517211 on 18363.385, windows defender virus scan was turned off, had to turn it back on manually.
Printer issues
Microsoft addressed some printing issues with the release of Windows 10 update KB4517211. However, it looks like the update broke something new. As soon as a Windows 10 user attempted to install the update, all the printers were greyed-out.
After the installation on a client PC all programs including Office reported “No printer installed” (not even the Windows internal ones – in “Devices and Printers” all printers are grayed out) – but the web interfaces of the printers were accessible via browser (status ok).
In addition, the message “Print spooler service does not run” was displayed – manual start of the service was not successful either.
The user managed to fix this issue by resetting share on WSUS. Furthermore, the uninstallation of KB4517211 brings back the printing functionality.
At the time of writing this article, there is no workaround available for those who are experiencing these issues. You can uninstall the update from Settings > Update & security > Windows Update > View update history > Uninstall updates.