External user invitations blocked in Entra ID B2C tenant after bulk upload

Hello,

I am experiencing an issue in our Microsoft Entra ID where external user invitations are currently blocked.

Recently we performed a bulk upload of users into the tenant. After this operation completed, we noticed that inviting new external users no longer works.

When attempting to invite a user, the portal shows an “Insufficient permissions” error even though I am signed in as a Global Administrator.

In the Activity Log / Audit Logs, the message shown is:

“Invitations from this directory are blocked.”

We have verified that:

External collaboration settings allow invitations.

The invitation is attempted by a Global Administrator.

The issue persists even when inviting a single user manually.

We only have a DEVELOPER support plan, please give any insights on how this can be resolved

Thank you.