I mark my 1/4-inch seam with a strip of masking tape. That way I know as the fabric is going through.

I'm thinking the seam allowance wasn't included in the template.

I think and inch and a half is too much to just be a seam allowance problem. There has to be more to the issue. As others have said, maybe the seam allowance wasn't added in.

I agree with many. Perhaps the seams were not taken into account.