Completing simple tasks or tasks from 'Task Report Macro' is unreliable

Summary

Completing tasks from the Task Report Macro does not yield the correct results. Sometimes the task checked is not marked as complete after refreshing the page in the Task report macro.
Other times, the wrong tasks are marked as complete (mark 1 task as complete but other tasks are marked as complete on a different page instead) and the user cannot check/uncheck the same in the original page.

Steps to Reproduce

1. Mark a task as complete from the Task Report Macro or from the My Tasks page in your Confluence User Profile
2. Check the page where the tasks is located.

Expected Results

The task is properly marked as complete all the time.

Actual Results

The task is not marked as complete and other tasks on the space are marked as such.
OR
No tasks are marked as complete at all.

Notes

• This issue is triggered randomly.
• It also happens with single tasks added to pages
• Sometimes, the following message is displayed when trying to check a task:

  Oops! Your task change couldn't be saved. There could be a few reasons for this. Dismiss.

Workaround

For pages using the Task Report Macro. It might help with simple tasks as well.

1. Open the page on which the phantom tasks appear
2. Copy all of the content
3. Delete the page
4. Re-create it, and paste in the original content