Are you using JSL?(Sorry, I'm unfamiliar with alteryx and s3.)
Can you print the the name to the JMP log just before you upload it? I'm guessing it won't have the date added, and you'll need to work back through your JSL to see why.
Or, perhaps the question is about turning the formula into JSL? Can you show the formula that added the date and the JSL you use for the upload?
Craige