Facepalm: Things that are certain in life: death, taxes, and Windows 10 updates that cause bugs. Once again, Microsoft has acknowledged a problem in the May 2020 update. The error affects the Network Connectivity Status Indicator (NCSI) icon in the taskbar, showing a user to be offline even when there is a connection---and that can confuse some apps.
The Windows 10 May 2020 update was found on 7 percent of all PCs at the start of the month. While it's landing on computers at a faster rate than previous updates, it's not without its problems. As reported by Windows Latest, cumulative updates in June and July have helped, but some users still see a yellow triangle in the NCSI and the "no internet access" message.
Despite what Windows might say, those affected by the problem aren't actually offline. It's still possible to load up a browser and surf the web as normal, but apps that rely on Windows 10's internet status to make a connection are unlikely to work. These include Cortana, Microsoft 365, OneDrive, the Microsoft Store, and Spotify.
It's speculated that the problem could be related to VPN or proxy use. Microsoft acknowledges the issue in a TechNet forum post, confirming that the issue is being investigated but hasn't yet been resolved. The NCSI error reportedly dates back to before the Windows 10 May 2020 update launched, affecting some testers in the Release Preview Ring.
The "No internet connection" bug can (possibly) be fixed by editing the Registry, which can have disastrous consequences if not done correctly. To correct the issue:
1. Type Registry Editor in the search box
2. Click on the app when it appears in the panel and allow it to run
3. Navigate to "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NlaSvc\Parameters\Internet"
4. Highlight 'EnableActiveProbing' and change the value from 0 to 1
5. Click on "Okay"
6. Close the Registry
7. Restart the PC
Note that this solution hasn't worked for everyone, but it's worth a shot until Microsoft release a fix, which will doubtlessly add new bugs.