Hey Matthias,
We raised a PMR and eventually got to the bottom of this (sorry for not updating !)
Turns out that this is an issue with the FTP library - the file was being returned marked as "OBJECT" - and not "FILE" in the response from the ls that's done on the server. I don't understand if this is a problem with the library or the FTP server - I suspect the server.
However..the library was ignoring this "OBJECT". There is a flag -
MQSI_SFTP_DEPRECATED_PARSE_LS_ENTRIES: '1'
setting this in server.conf (or any one of the various places that you can set env vars in ACE) worked and the lib recognises type "OBJECT" as "FILE" :-)
thanks folks,
john