Problem

-- files with name containing spaces prefixed and suffixed by numbers(e.g. "123 4.txt") not picked by FTP delivery exchange. no issue for files such as "12a 4.txt", 1234.txt, ...
-- 550 File not found when polling file with specific names
-- Transport_Failure(Error(Incomplete data received),
Transport_Error(com.cyclonecommerce.tradingengine.transport.FileNotFoundException: 550 File not found; command=RETR 4))

Resolution

* install Interchange 5.10.1_SP7
* valid for all OS