Can anyone in Let’s Encrypt ops speak to whether or not there were any attempts to secure a validation for myetherwallet.com or any subdomain labels of it this morning?
If so, did this validation fail for lack of DNSSEC validation? - No - See edit
Edit 1: DNSSEC validation would not have arisen as an issue because DNSSEC is not enabled for the domain. My remaining question is whether such a validation was attempted and, if so, for what cause did it fail?