Hi Gil & Richard,
I believe this error is caused by a configuration issue on OneDrive's side, but not using it myself, I can't really help.
I was going to point to the previous discussion in https://moodle.org/mod/forum/discuss.php?d=353376 but I see Gil has already posted in that one, without much luck.
Looking at that previous discussion, I don't think this issue is specific to MoodleCloud, so maybe it's time for a new issue on Moodle's bug tracker. I'm not a OneDrive user myself, but if one of you could precisely write, on the tracker, the steps taken and the errors encountered, it might help debug this issue and resolve it for everyone.
Mathieu