"Another course contributor modified the course. cannot save changes." single-instructor course.

Good morning. Teachers reporting a repeat of an issue from March 2016. They cannot save changes because "another course contributor modified the course." These are single-instructor courses. Here's a link to earlier discussion: Re: I can't save changes in my courses. Does anyone else have the same issues? This did get resolved once and now the issue is back. Is anyone else experiencing same?

Thanks!