One of the biggest selling points of Windows 10 May 2019 Update, version 1903, that was released earlier this year was the ability to "legitimately" defer Windows 10 feature updates. Calling it "the update that brings some sanity to the Windows world," apparently the option to defer the update for up to 35 days disappeared for some users.
It appears the bug only affected the Pro version. Woody Leonhard kept a track of this issue for weeks, calling it "one of the most frustrating bugs in Win10 version 1903." He explained that if you change the deferral settings from Settings > Update & Security > Advanced options, and then rebooted your machine, "that part of the advanced options dialog disappeared entirely."
With Windows 10 November 2019 Update, version 1909, here, it would have obviously annoyed users since what else was even the point of this new option. But, Microsoft resolved this ahead of this week's public release of version 1909.
Windows 10 Pro 1903 deferral setting bug was addressed with KB4522355
The Windows maker addressed the issue with the release of optional, non-security update KB4522355 (build 18362.449), which was the second cumulative update for October. Installation of this update brings back the deferral option. Microsoft never officially acknowledged or listed it as a fix in the aforementioned update's release notes.
As we mentioned earlier, Windows 10 version 1903 is at its most stable state. However, the ISO files are no longer available for that particular version. Since Windows 10 1909 is a smaller, Service Pack-like update, we are hoping this particular version ends the streak of bugs-full feature updates. However, we would still recommend to wait for a few weeks before installing this version unless you are okay to deal with any unknown bugs.