Some users are experiencing connectivity issues with OneDrive after updating to Windows 10 2004. This seems to be caused by an incompatibility with older devices and the Files on Demand feature in OneDrive. Users should still be able to access their files through the OneDrive website or mobile app. Microsoft is currently investigating and working on fixing this issue, but in the meantime they’ve released a troubleshooter that can be ran to try and fix the connectivity issue. For more information, feel free to check out the link below.

Source: Windows 10 2004 breaks OneDrive connectivity for some users