AutoCAD Inventor :: Sheet Metal Flat Pattern Errors

I have attached a small Sheetmetal I-Part that is fairly representative of a lot of the work we wish to accomplish using Inventor. Stepping through the table and activating each row therein changes the model smoothly and there are no errors. But as soon as I create a flat pattern for ANY of the rows, I get the error message shown in the first of the attached JPEG images. When I choose Accept, Inventor creates the Flat Pattern, but there are no errors that I can discover (see 2nd JPEG), not even when I expand all the children.

Now that a Flat Pattern exists, activating other rows of the Table result in the error message each time. Delete the Flat Pattern and stepping through the Table returns no errors at all. The folded part is robust and the flat patterns have no interferences or obvious errors.