My co-workers and I have had this issue for some time but it only happens randomly. Attached is a screen shot of a section view of a sheet metal part. When you try to dimension the edge flange you get the error seen in this picture. Something really weird....when you go back to the part and try to measure the flange in that environment, you can't. Has anyone seen this and is there a fix. All we know to do is to sketch a point on the line and dimension to it.