Microsoft 365 Tenant-to-Tenant Migration: Users Losing App Data After Domain Move – How to Fix?

After completing a Microsoft 365 tenant-to-tenant migration and moving the custom domain, users can sign in successfully but are treated as new users in third-party apps (data not visible).

Even though email addresses remain the same, the underlying Azure AD Object IDs change, which often breaks data association in SaaS apps.

How are others handling identity mapping and app data continuity during tenant consolidation or school trust migrations?

We’ve seen teams plan this more effectively using purpose-built tenant-to-tenant migration platforms like CloudBik, which help manage identity transitions alongside Mailbox, OneDrive, SharePoint, and Teams migrations.

Interested to hear real-world approaches and lessons learned.