You have assigned a copy migrate policy to a PST but it fails with the error 'Copy migrated X messages out of Y that matched from Z found. There were N errors but this was below the threshold.'. In the PST Enterprise Client tracing you can see:
17 16:32:59 071504 MarkMessageWithCopyMigrateTag SaveChanges returned hr = 0x80070005
17 16:32:59 083783 MarkMessageWithCopyMigrateTag SaveChanges for CopyMigrateTag failed 0x80070005
17 16:32:59 095633 HandleCopyMigrateAction: abort_reason = ArchiveOne Policy was unable to tag the message with the copy migrate time. Go to http://www.barracuda.com/support for further assistance
In order to keep track of which items have been copied from a PST file already (and thus avoid data duplication), an additional property is added to the original item in a PST to prevent it from being copy migrated again. In this case MAPI error 0x80070005 MAPI_E_NO_ACCESS is returned. The indicates that the user has insufficient permissions to modify PST data.
You may have applied a restriction in regards to creating or modifying PST data to the affected user via Group Policy, or another configuration method. You will need to remove this restriction so that PST Enterprise is able to process the user's PST data.