External User can't open library in Windows Explorer

for our SharePoint online, external users can sign into SharePoint ,no issues on the Internet Explorer, but when they tried to open the libraries on Windows Explorer, there is an error says "External shareing is disabled, Guest User is Signing-in but external sharing is disabled." but we have set the sharing on the site collection to "allow external users who accept sharing invitations and sign in as authenticated users"

I remember that this was not an issue before, until recently changes in messages when "Open in Windows Explorer" link is clicked.

Thanks a lot