Before MODSOURMAN-422 was released, single record imports had provided record with no "order" field . It led to the problem with log display (no log shown) for single record create/update., which is documented in UIDATIMP-1136 bug
After MODSOURMAN-422 release for the new single record imports (create) new records with empty "order" field were not created, but records that were imported before MODSOURMAN-422 still have "order" field empty.
To prevent the occurrence of this problem for the single record update operations on the already existent records with empty "order" field we need to run these updates at any time:
UPDATE {tenant}_mod_source_record_storage.records_lb SET "order"=0 WHERE "order" IS NULL;
UPDATE {tenant}_mod_source_record_manager.journal_records SET source_record_order=0 WHERE source_record_order IS NULL;
Where {tenant} - the owner (tenant) for which you want to run the update.