Twitter Player Card not validating



I have applied for twitter player cards and just received an email saying my URL wasn’t validated. I have no idea why, the checklist in the testing tool ( shows all green circles. The URL I submitted was

The email I received contained no explanation. It only read:

"The URL you provided for to use the player card did not validate. Please make sure the page contains valid metadata, then reapply for a Twitter card.

Thanks for your patience. See you soon!"

Can anyone guide me to finding the source of the problem?

Thank you