Hi @nedaura,
Just so I understand you correctly, is your issue that files are missing from posts that have been migrated already, or are you just looking for a way to migrate them all at once?
Regarding why we do the migration lazily, it’s to avoid downtime while it takes place. At the time that we were making that change, I tested on a copy of our nightly build server, and it was 30 minutes to an hour to complete. We’ve had a customer’s system containing a lot more data take 20 minutes just to add a column to the Posts table, so this taking over half an hour on a smaller data set wasn’t an option. We have some plans in the future to do larger migrations just in the background instead of just on demand like that one was done, but it’s still pretty far out