Trouble to bring external users

[ypz123]

We have been able to invite external users to our sharepoint site w/o any issue,  However we are having trouble to do it now - we tried multiple ways of grant permission,  user keeps getting access denied msg when tried to access the site.    We tried gmail as well as O365 account from another tenant which has full license from the source tenant.  Anyone has trouble with inviting external users?  Unsure what has happend. 

[#2]

Are you the admin? Have you verified that nothing has changed on tenant/org. level for SharePoint when it comes to permissions?

https://docs.microsoft.com/en-us/microsoft-365/solutions/collaborate-in-site?view=o365-worldwide

[#3]

@ChristianJBergstrom  Yes, I am the tenant admin and we have not changed anything.  I have verified all external setting.  Nothing being changed.

[#4]

Then you should open a support ticket with Microsoft.