I know it's been a while, but I finally got this issue resolved. Not sure if it'll be a moot point for us on FC unless Gambit starts running tasks again, or FC contracts with someone else who provides the Crowdflower/Delores Labs task..but for anyone that was impacted by this and works other GPT sites that run the tasks, he's what was discovered.
Recap - the issue was after working the first page of a task, when submitted, received an immediate disqualification message that simply said my submission was denied due to poor quality work. There was no page that indicated which item was in error. Very unusual for those who've worked these (typically you get a page that flags the incorrect answer before one would potentially be disqualified).
Apparently Crowdflower was experiencing a higher than usual volume of spammers - people who would work the tasks and put junk in the answers to get paid (have no idea why people would do such a thing). To clean up their task results, and save their clients from paying money for bogus results, they did a massive IP ban on worker IDs with a high volume of submissions. Since I tend to work a lot of tasks (on this site as well as others), my IP was picked up by mistake in this sweep.
So, if you were someone who worked a lot of tasks from Crowdflower/Delores Labs (Mechanical Turk) - I suggest trying another task, and after you get the immediate disqualification page - submit feedback and request whomever works your feedback to check if your IP was inappropriately banned. Explain you heard about an IP ban done a couple months back to clean up spamming and you wanted to make sure your IP wasn't accidentally included. That may be the fastest way to get them to check and fix the problem.
I already tested by working a task on Mechanical Turk today and was able to successfully submit the task - first time in about 2 months.
Hope this information helps anyone else who encountered this issue. May not help here at the moment (since there are no tasks running), but if you work those tasks elsewhere, maybe this will get you working them again.