When attempting to validate a challenge against my trailhead playground org, it spins and spins for 5 minutes, then eventually comes up with a red bar with nothing in it, as thought to tell me I did something wrong in the challenge.  

Hi
After completing the trailhead module, I am not able to check challenges. After clicking on button, It is showing as nothing happend. No Error, No Success, No warning. I am facing this issue from 30th Nov. This issue has been fixed for 2-3 hours today evening but Issue has been started again. I have clear my cookies, checked all browsers(Mozilla Firefox, chrome, edge), on diffrent OS(Windows and Linux).