I don't know if I'm the only one who has this problem, but many times when downloading an archive from Workupload.com, one or more files get skipped for some unknown reason. So this is just a courtesy alert to check your downloads from this domain for completeness. Hopefully, it's just me.
I had this problem too. Maybe it's a coincidence, but when you click the "Download archive" button, a new tab opens and then the download queue starts, I used to close that tab and always had missing files, but now I keep it open and it works fine. I still check tho,