Few files not being listed in OIC List files until touched or saved again

Summary:

We have Fusion scheduler placing file on to FTP folder, which in turn will be listed and processed by OIC , we do not see those files listed in OIC. But when try to change and save the same file that is getting listed in OIC and getting processed.

Not sure If I should consider this as File issue or listing issue with OIC as OIC is able to List few other files in same directory, when placed Manually and also Fusion placed files when edited and saved.
I have checked file permissions before and after saving the file they are same but file is getting listed once we edit something and saved. Please advise if any suggestions to understand if it is a issue with file or OIC FTP listing in Gen3.