Here is an update:
Worked with McAfee support to resolve our issue. We deleted our old records from the DLP 2.2 database, and then ran the DLP migration tool to convert the remaining 51,000 events. The DLP migration tool was able to handle this amount of records.
I am having the same issue. I would like to speak to you offline if you don't mind. I am working with support right now and they are acting as if they don't know what the issue is. Let me know if you have a min or two available for a quick discussion.