Missing Messages but can see I've received it
This is a recurring issue with no solution and not a user settings error. Occasionally after receiving an e-mail, I need to find it again but it is no longer in my inbox nor can I search for the message.
The very odd thing is the sender's email address will show up as a top contact if I search by their address. Then, the side bar will show me that person has sent me X messages beginning with one titled Y. However if I search for those messages by title or their email address, nothing shows up. It's not in inbox, trash, etc. It hasn't been deleted because of time as older inbox messages still exist.
Very frustrating & costly bug, how is this possibly happening? Now, I cannot schedule a medical appointment because of missing information from this email I can't find.

Hi there,
Could you please message us on Twitter at @YahooCare or on Facebook at Yahoo Customer Care? We'd like to look more into the issue you're experiencing. In case you do not have a social media account, we are also available at: help.yahoo.com
Looking forward to your reply!
Thank you,
Yahoo Mail team