This solved the problem for me as well, but I do have a question... or a scenario..
So I pulled the flanges off my flat, flattened, and did the cut. The way I drew my cut was perfectly tangent with the part sketch in the flat. So when I measured my flange length I measured it in the flat. Of course once I flattened the flanges they were longer than the sketch and therefore there was excess material on either side of my part. My solution was to create a new sketch on the flattened part and measure from the bend line to the end of the part, go back and use that number for the length of my flanges. It got me close enough, but I was wondering if there might be a more accurate way to achieve this.
Math was never one of my stronger skills, and I'm still trying to master all the sheet metal settings, so I may be missing something obvious here.
EDIT: Sorry - I think what happened now that I've had some coffee is that at first I didn't measure my flanges and just pulled them past the cut, which left excess material. Then I attempted to measure from the sketch which wound up being too short. Then I measured from the flattened part which is "close enough" but just wondering if there was a more technically accurate way to achieve this, or does one just over build the cut?
Thanks!