Remapped images from hugin may contain holes; enblend (3.1) sometimes blends these incorrectly leaving holes in the blended image.
A set of example images are at:
wget http://www.gawthrop.net/bug/bug.zip
(to big to attach below)
bug0000.tif--bug0007.tif are the remapped images.
bug.tif is the result of:
enblend -o bug.tif bug000[01234567].tif
nobug.tif is the result of...