Returning solidworks user, I haven't been able to get a tube to flatten with solidworks' sheet metal commands

So I've tried several methods, here is one:

On this one I'm using the flatten command. Here's what happens when I hit flatten:

Now, I'm getting this same result, no matter which method I use, flattening, bending, convert to sheet metal, etc.

Following the exact procedures shown on the several video tutorials I found online. Beginning to wonder if there's some setting buried somewhere that's causing this issue.  I uploaded the part file to see if others get the same result.