Cloud Only to Hybrid

Hey guys, I have a case open for this one too (94795987) but thougth i'd post here as i really need the issue fixed and maybe somoene has come across it before!

We were assured that it was possible to match and migrate content for hybrid accounts, however when we come to do the migraiton we get the error as outlined here:

The steps we have taken are:

  1. Source tenant has cloud only accounts, no federation, no azure ad connect
  2. Target tenant has hybrid accounts, federated domain, azure ad connect
  3. In the target domain we have provisioned remote mailbox users on premise, synced them to the tenant and licenced
  4. Both source and target accounts work perfectly, can login to them etc and view mail no problem
  5. We have created a custom CSV file and matched the source cloud accounts with the target hybrid accounts
  6. We then run a migraiton task which fails with the error in KB 276450

I've done the following just in-case

  1. Ran another match task and cleared the existing mappings
  2. Delete the users entirely from on demand
  3. Ran a discovery so the accounts re-appear
  4. Re-ran the match task using a custom CSV and sucesfully matched the correct source and target UPN's
  5. Re-ran the migrate task but yet again the task fails with the same error

I'm a little baffled as to why, hopefully the support ticket will be resolved, if so I'll post here. If anyone else has seen this please shout out. I'm trying to get the migraiton over the finish line and this is holding us up.