After importing leads with Matchmaker enabled, user sees Duplicate Error Logs with the following Error Message text:
"Unable to report on duplicate records. DuplicateRecordItem : Duplicate Record Sets can only contain 300 Duplicate Record Items"
Salesforce Duplicate Management is unable to process more than 300 records at a time for the same match. This is a known Salesforce Data.com limitation.
In this scenario only a subset of the leads you have bulk uploaded or updated are matched correctly before the error was thrown. If performing a bulk upload or update with more than 300 leads all matching to the same company, our recommendation is that you run the one-time lead matching batch from the Matchmaker Configuration until all of these leads have been successfully matched.