Unable to save the file for apex code : GiveWorkThanksAction.

Need quick help. Thanks in advance.

Unable to save the file for apex code : GiveWorkThanksAction.

Need quick help. Thanks in advance.

I am trying to complete "Automate Your Business Processes:  Build an Automated Workshop Management System: Automate Post-Workshop Tasks with Invocable Apex " and when I click "verify step" I get -
Challenge Not yet complete... here's what's wrong: 
Couldn't find the "Thanks" badge in the instructor's Chatter feed after completing a Campaign.

I have rebuilt the flow and the APEX and I can't get it to complete, but the "Thanks" badge IS in the insturctor's feed when I change the campaign to complete, so everything seems to work, I just cant get it to "verify"

I'm doing the simple lightning components challenge and have hit this problem in my existing trailhead org and a brand new dev org that I've just created:

Challenge not yet complete... here's what's wrong: 
There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: QVWBQHAG