Hi Vaibhav,
Msecs to wait before modification do not work in FTP scenario. it works only with NFS.
Did you find the root cause why the file is incomplete? I mean did third party confirmed the incomplete file is generated from their system or PI is picking the file before the file completely written in the FTP folder.
what is the polling time of the sender FTP channel? you can schedule the channel.
Cheers
Hidayat