Demystifying Hybrid Free/Busy: Finding errors and troubleshooting

Michele71 , the way I would see this working is if the Google Workspace Migrations would be like Hybrid Migrations, meaning that we would convert the Mail User to Mailbox in EXO at the end of the migration and we would copy the data into a disconnected, hidden mailbox in EXO (move destination shard) and the Target User would be Mail User all this time until switchover. However, notice that this would be a huge design change and I am not sure if this approach would be taken in consideration. There might be other ways to have calendar sync jobs / caching data but also this would be a design change, and nothing would be immediate. You can still open a support case or check with Fasttrack team to see if there are any other workarounds. On the Google side, during migration, maybe Google users would share the calendars with the EXO Users? Share your calendar with someone - Google Calendar Help