After some more troubleshooting, I found that the issue was with my MongoDB server. In the current k8s setup, we were using our own MongoDB and MySQL servers. The MongoDB server was running the latest version, 7.0.12, which seemed to have caused the issue.
When I tried running the platform with the default tutor configuration of MongoDB, which used the MongoDB 7.0.7 docker image, everything worked properly.
So, I downgraded my MongoDB server to 7.0.7, and now there is no error while importing the demo course (even without importing the library first).
But I still don’t understand how this small version change can cause this error, as it’s all within version 7 of MongoDB.