FTP files to USB storage attached to CiscoE3000 router

[ftpnewbie23]

I have a strange problem.
I FTP'd files to my External Hard Disk attached to Cisco E3000 router and with My Network Places connected to the shared drive, I could see folders getting created and files coming into folders nicely. It took about 10 minutes for all the files to come in and when I looked them up again through mapped drive, the folders show up as files and size as 0KB.

I look them up using Filezilla client and they show up as folders but they're empty.

I can delete these folders using FileZilla but I cannot delete from the mapped shared drive because I get a message "File / Folder could not be found".

I have no clue whats going on and where to look for answers. I don't even know if this question is suitable for this forum or I should be asking somewhere else.

Any help resolving this or in pointing me in the right direction will be highly appreciated !

Thank you !