FTP and File Manager problems

Hi there, trying to upload FTP files to my site, they transfer through and show up as in the directory, but once the directory refreshes they are not there. Tried this with both an FTP client and the online file manager.

I’m assuming this is not a ‘feature’ - can i please get an answer help on this.

The file i’m trying to upload in this instance is a html verification file for zoho mail.

The only reason I can think of why a file would be automatically removed is because it is over the 10MB file size limit. However, verification files are not supposed to be that big.

Do you only see this problem with this specific file or also with other files?