DSA.log contains
08/17/17 16:53:05 (GMT+01:00) Target JobID:0 -> Starting next matching: sIDHistory;objectClass
08/17/17 16:53:05 (GMT+01:00) Target JobID:0 -> This is a LOW priority matching rule
08/17/17 16:53:05 (GMT+01:00) Target JobID:0 -> No source object includes this matching rule
Which means that when DSA converts ObjectSID->SidHistory to search in target for matched objects converted object doesn't have SIDHIstory attribute because it has been skipped in sync options.
Another case:
08/17/17 16:53:05 (GMT+01:00) Target JobID:0 -> Starting next matching: objectGUID;objectClass
08/17/17 16:53:05 (GMT+01:00) Target JobID:0 -> This is a HIGH priority matching rule
08/17/17 16:53:05 (GMT+01:00) Target JobID:0 -> No source object includes this matching rule
In this case DSA tries to convert source Matching attribute (ExtensionAttribute15 by default) to objectGUID and resulted object has empty ObjectGUID.
This means that Source object has not been matched in reverse sync and ExtensionAttribute15 is empty and cannot be converted to ObjectGUID