A sync will skip the transferring of a file whenever the source and destination copies match in name and size.

A file can also be skipped when it has been modified since the time that the sync started. When this happens, the External Logs will show the following message:

Detected a change in file during sync

Skipped files will be retried by subsequent syncs.

If a file is repeatedly skipped by syncs then determine if the file is being continually updated or is being updated at the same time that the sync is trying to transfer it. Configure the sync so that it runs during a timeframe when the file is not being updated or changed.