I got these parts handed onto me and we cant get a hold of the guy that did them, so here i am...

i have this simple sheetmetal ring that is throwing a error (refer attached screenshot) and can't see what might be causing it or how to fix it. this has happened to a HEAP of the parts he has done and i have been rebuilding them as i find them but it is getting beyond a joke now and taking to much time. i can't for the life of me work out a way to fix it. if i delet the problem features i can't perform and unfolds (and loose my flat pattern). if i delete the sheetmetal feature altogether it won't let me convert the part to a sheetmetal part again.

any help appreciated.