Yeah. I started the stitch in my older-version environment. Besides blending out all of the interesting stuff on several images, it blended fine.
Yes, I've started to use the workaround of marking big parts of the later images as exclude so that a big seam is seen by enblend. Apparenlty marking the small airplanes with an include mask is not sufficient. Things are becoming complex with all those masks and the pictures being too small to see on the preview. And some images having to be made immobile relative to each other because I had to manually align them. etc etc.