ODMSP: There's a discrepancy between source an target amount of files and/or sizes (4372982)

After migration by ODM, there's a discrepancy between source and target number of files and/or sizes.

There are multiple factors, that may affect the final outcome. Before verifying what is causing discrepancies, please review SharePoint migration limitations, that outlined in this document: On Demand Migration Current - User Guide (quest.com)

In addition to that, the following factors may affect it:

• Are all versions migrated or only the latest? NOTE: For versions there is a size limit of 512MB, this will also cause a size discrepancy for files that are larger than this, only the latest version will be migrated.
• Are there 0-byte size files?
• Also include recycle bin contents that accumulates with use 

Lastly, after the migration process, Microsoft is running an indexing process in the backend. We've observed delays of over 24 hours in reported statistics until actual sizes are reported.