Update to 21H1 vanished from WU

Hello.

I was on 1909 when Windows forced 20H2 update on me at the end of April. Fortunately, everything went fine, except that CBS.log still shows several files as having user or permissions set twice.

Somewhere at the beginning of June, I got offered optional update to 21H1 but I decided to wait. Then, on June 30, WU removed 21H1 and replaced it with optional update "2021-06 Cumulative Update Preview for Windows 10 Version 20H2 for x64-based Systems (KB5003690)".

I didn't want to install it, so I pressed "Check for updates" button (with green mark) hoping that 21H1 feature update offer would return (it worked in the past for 1909 feature update that similarly vanished).
But instead of getting 21H1, WU found new update and installed "2021-06 Cumulative Update Preview for .NET Framework 3.5 and 4.8 for Windows 10 Version 20H2 for x64 (KB5003537)".

So WU forced a preview update on me... then I decided to install the other optional one, hoping that WU will then show 21H1 after reboot.
But of course it didn't happen and I am wondering why is it and is there some non-voodoo way to get that feature update back and simply use WU to update my system to 21H1?
I am aware of Update Assistant, downloading Enablement package (which is no longer listed on MUC) or using ISO to upgrade windows, but before getting rough, I'd prefer to use WU if possible. BTW, I had no such problems on my W10 running in VBox...

My current OS build is 19042.1081

Thanks in advance.

My experience is that Build 19043.1082 (KB5004760) is only available as a download.
June 29, 2021—KB5004760 (OS Builds 19041.1082, 19042.1082, and 19043.1082) Out-of-band (microsoft.com)

Thanks for your input.

This article specifically says feature upgrade to 21H1 is not available through MS Catalog. The only options, according to that source are Windows Update/Microsoft Update and WSUS. Another article doesn't mention MS Catalog either but instructs to check WU for presence of optional 21H1. And after all, I had it there for almost a month.

The enablement package is KB5000736. Using WU, it is ensured that the last SSU would be installed first, so I prefer that method. It is starting to get weird...

This is a snapshot taken from a youtube video that shows how it looks/looked:

That KB5000736 was installed back on 5/23/2021 on a few of my computers.

Do you have something like: Feature Updates (1) Feature update to Windows 10, version 21H1 Successfully installed on 5/23/2021 in your WU update history?

I don't recall if it was automatically offered or not. The image I posted is the History and shows that update on 5/23/2021. I'm now on Version 21H1 (OS Build 19043.1081), soon to be on 19043.1082 which I already have on 2 other Desktops and 3 Notebooks.

KB5004760 Windows 10 2004 19041.1082, 20H2 19042.1082, 21H1 19043.1082