Probably because of this
viewtopic.php?f=15&t=9986&p=39157#p39157
Zero-byte files are automatically trapped by the logic that checks for same content but different name case or properties (zero-bytes means the contents must be the same, because neither of them have any content). If they have different properties (LastModified) and/or name-case, that section will activate (rather than ignore them altogether).
The default Action for such files is 'Do nothing, skip the file'. See the other thread for alternate options.
viewtopic.php?f=15&t=9986&p=39157#p39157
Zero-byte files are automatically trapped by the logic that checks for same content but different name case or properties (zero-bytes means the contents must be the same, because neither of them have any content). If they have different properties (LastModified) and/or name-case, that section will activate (rather than ignore them altogether).
The default Action for such files is 'Do nothing, skip the file'. See the other thread for alternate options.