@Josh, !!!!!!!!!!!!!! You fixed it!!!!!!!!!!!!!
It was my fault for not giving the version of WooCommerce I was using. I was uploading an older version to duplicate a site that I was working on. That was why I uploaded copies of the files in question as a zip file, so that you would have copies to test.
As I mentioned to Otto, using sftp did not make any difference. The same 5 files failed to upload. The file names appeared briefly and then disappeared.
I would like to know what you did to correct the situation, if you are allowed to tell me.
Thanks for looking into this, especially after the tech support person I talked to said there was nothing that could be done!
Marking this 'Resolved'.