I hope that in the future you’ll allow other instructors to edit lessons in a course they’re sharing with their colleagues. It can really help them fix things faster when one of them is not available.
Concerning the issue, as I said, it happen when a co-instructor add a new lesson. Everything seem to be okay after publishing but after few hours, it’s automatically get unassigned in the course. The worst part is that if it was a quiz that was set by the co-instructor, it simply disappear and the instructor remain with the quiz results only.
When you go to check in quiz attempts, you see the results without the course where they belongs to yet the course is still there.
https://drive.google.com/file/d/1ESyXwqg4CRnmSENCLmyS7sCXeO80Qdcv/view?usp=sharing