Problems Migrating mailboxes - Unable to provision jobs from the current recipient. The owner recipient isn't a valid user.

Unable to provision jobs from the current recipient. The owner recipient isn't a valid user.

I am also receiving a message fro a number of users that I deleted from the Office 365 system after starting this migration:

A cloud-based mailbox wasn't found for "<username>". Create a mailbox for "<username>" in the cloud-based organisation and try again.

Following a suggestion from Jolin Qiao I have taken the following actions:

1. Deleted the users for whom I did not want cloud based mailboxes from the in-house exchange server
   (their mailboxes were 'marked for deletion')

• Ran the CleanUp Agent in Exchange System Manager.
  The 'deleted' mailboxes are now marked with a red dot/cross

• Created a new user in the O365 system for one of the mailboxes that is failing with the
  'Unbable to provision jobs...' message.

• Edited the batch migration job but didn't actually change any values.

• Clicked the 'Resume' button.

• After a few minutes I clicked on the 'Refresh' button and the batch job had a status of 'Synced'.

I still had all the same errors :(

This is urgent now as I am planning to complete the migration on Fri/Sat this week.