Can't change reading order

I have a document that is fully accessible except for one item that is completely wrong. I have a tagged form field that is an item structure that is in the incorrect reading order. I cannot move it to the correct reading order location. I cannot delete it. Even if I clear the page structure, this particular element will not delete. It also won't show up in the tag structure, even though I've tagged it several times. There aren't any unmarked annotations, so I can't get to it that way either. Does anybody have any ideas how to resolve this issue?