Thanks for all your efforts. May I ask if the solution can also be applied to my case? It looks the same, but there are still some differences.
Some files are corrupted when teacher are marking on annotation page, however, most submission are fine. Maybe these files are not supported format. Another questions is, teachers can download the file, but they can't save grades on this page (using rubric). Please check the following image:
We are using moodle 3.10. Hope anyone can provide some ideas.