Dear Paul, dear Leo
unfortunately I got the same problem in my Moodle Installation you described, Leo. Leo and Paul, did you get any further and did you find out a solution for the problem yet?
My nextcloud installation is up to date (15.0.7) , moodle is version Moodle 3.7.7 (Build: 20200713).
Leo, you are a teacher in BW, aren't you? So maybe your moodle is hosted @ belwue like mine.
Thanks a lot in advance for your reply!