Nice model!
Looking at ST’s model I went back to mine and discovered to my shame that the holes actually ARE in the Mesh!
Apologies for the confusion!
I realize now that in the cases I was looking at the orthophotos I created from the shaded models still had the large triangles of the RC-model-wrapping in the background, so it did not show in the orthos…
This fault does not show up in a slightly different alignment of the same set.
Although I did run that one through Photoscan first and used the undistorted images.
This results in a better alignment but sadly in a slightly blurrier texture, but that is another issue…