Cannot export 4K video

[Austin]

Without the export log to tell us anything for sure, all I can do is offer one last speculation. Perhaps the exported video is going to a Windows Protected Folder, which will fail for permissions reasons:

Export fails with "[consumer avformat] Could not open"

Thank you for replying with that excellent workaround! https://support.microsoft.com/en-us/help/4046851/windows-10-allow-blocked-app-windows-security And from Protect important folders with controlled folder access on microsoft.com: Protected folders are specified when controlled folder access is configured. Typically, commonly used folders, such as those used for documents, pictures, downloads, and so on, are included in the list of controlled folders.