I’m reviving the topic. I’ve been having the same problem for about a week. Tasks didn’t load and the loading circle was spinning forever. Our site is on a hosting account using cPanel and the log records were not as detailed as what you shared here. Maybe it’s due to OJS version difference, I don’t know… Anyway; Thanks to what you wrote, I made an inference and solved the problem.
When we first set up OJS, we did some tests to understand the system and workflows. We couldn’t delete the submissions from the admin panel and I deleted these submissions from the database to avoid confusion when we start receiving real submissions. However, tasks of these submissions remained. I thought that OJS couldn’t load the tasks because these submissions were deleted and the notifications table and the submissions table were related, so I deleted the old notifications (Instead of directly associating it with the submission id, a different method was followed, so I could not detect the notifications associated with the submissions I deleted) from the notifications table in the database. So, problem solved.