My workflow has a number of Request Data actions utilizing a couple of Content Types that create a task and send a notification with a link to a task. Pretty standard.
I have assigned a new task list to the workflow, and now tasks will still be created as usual, but when I attempt to complete the task by clicking the "Complete Task" button, the form closes, but does not show as complete, nor produce an outcome; so the workflow goes nowhere.
I have tried reverting back to the original Workflow Tasks list, creating new content types, and attempting to make the % Complete field visible in the form (which didn't work); none of these have solved the issue. I am at a loss.