I saw that there were a lot of comments on the contact.php form and not being able to submit. I also had this problem and after a handful of hours trying to find a solution, I went ahead and just went with formspree.io instead of the contact.php.

For future developers using this theme who encounter this problem. Just comment out the existing form and then add this. Once you've taken the 5 minutes to verify with formspree, this should work.