In trying to troubleshoot this problem more, I created a new file, test5.php, with just a text field and a file field using FB, like before; however, I did not remove the validation for the file field for this testing. As expected, I did not receive an attached file to my email.
I then placed a "yourfile.gif" file into my website and in the UE's Attachment panel I pointed to this file (the default file name shown when you go into that panel) rather than using the Server Behaviors dialog to select the Server File Name and Server Directory entries, like I normally would. That worked as I did receive the "yourfile.gif" file attached to the email.
I then went back to the Server Behaviors dialog in UE to point to the Server File Name and Server Directory entries, and again did not receive an attached file in my email.
I've enclosed the files for both tests for your review. The only code change I can see is in the associated WAUE files where the content of the WAUE_AddAttachment function is different, as expected. Works for a static file, but not for the serverFileName code structure.
I am curious. Have you run similar tests and did you encounter the problem I am having?
Thanks again for your support on this.