Specific sender not coming through to AWS Workmail inbox

I'm using Workmail for my organization, and have noticed that emails from one specific sender are not coming through to my inbox. Some relevant information:

• The email is not showing up in Junk/Spam or any other folders.
• There are no settings in the Workmail Inbound rules that would cause this email to be blocked.
• There are not settings in the SES Email Receiving rules that would cause the conflict.

The sender is getting a successful delivery status that reads:

Delivered (inbound-smtp.us-east-1.amazonaws.com:25:250 OK

Can someone recommend how to further diagnose this?