Getting an issue in logging into external tenant organization from Power BI desktop , Switching organization from PBI Desktop to other PBI tenants Login and Sign in from PBI Desktop only recognizing now Corp Tenant ID only not external tenant login ID.
Power BI Desktop has no login restrictions for external tenants. The only restriction is when it comes to sharing. Internal users are not allowed to share content directly from within the organization to external users, and there is no distinction between inside and outside the organization when logging into PBI Desktop or PBI Service. Unless your company's network security guidelines restrict the use of other domains.
I was able to log in to PBI Desktop using the two accounts in the screenshot, obviously they are not part of the same organization.