I had not entered this option.
Now I have done this and it works.
The viewing direction is aligned as intended, from one image to the next image.
Only the viewing direction of a specific photo is set to 0 degrees for unknown reason. Also on the second try.
It is also important not to have entered a viewing direction in the exif file of the photo. The field must be empty. If there is data in this field, it will not be overwritten. The original viewing direction is retained.
I will edit some more tracks and then report again.
Thanks for this tip.