As part of the June 9 Patch Tuesday, Microsoft released a patch for one of the issues that has blocked some Windows 10 users -- and Surface device users in particular -- from being able to apply the May 2020/2004 feature update. But even after patching, Surface Pro 7 and Surface Laptop 3 users (among others) still won't be able to immediately get the May Update.
After announcing on May 27 that it was starting to make the May 2020 feature update available via Windows Update, Microsoft also released a list of about a dozen previously undisclosed issues, which potentially could cause problems for anyone applying the May Update. One of those issues has to do with potential unexpected restarts for devices with more than one Always On, Always Connected network adapter. Surface Pro 7 and Surface Laptop 3 both qualify as these kinds of devices.
Microsoft released today KB4557957 (OS Build 19041.329), which, according to its documentation, mitigates this Always On, Always Connected issue. However, the Microsoft documentation for this also says: "To safeguard your update experience, we have applied a compatibility hold on Windows 10 devices with affected drivers or firmware from being offered Windows 10, version 2004."
(Windows 10 users with 1903 and 1909 also should manually install the KB4560960 (OS Builds 18362.900 and 18363.900) patch before KB4557957. However, that still doesn't make Windows 10 2004 available immediately, either.)
Any "seekers" with the Always On, Always Connected issue who manually check for updates in the hopes of downloading and installing the Windows 10 May 2020/2004 update will still get this message even after applying the June 9 patches:
"The Windows 10 May 2020 Update is on its way. We're offering this update to compatible devices, but your device isn't quite ready for it. Once your device is ready, you'll see the update available on this page. There's nothing you need to do at this time."
Microsoft officials have declined to explain why the dozen or so late-breaking blockers for the May 2020/2004 update were not disclosed until May 27, even though that feature update had been in testing for nearly six additional months beyond its completion date. I've heard from some of my contacts that these issues may not have been widely experienced until Microsoft began testing with Release Preview Ring customers and initial mainstream rollout recipients. But no one from Microsoft has stated this publicly.