There is a bug on Windows version 9.2.1735 (3d90379).
In conversation mode, in the Sent screen (Gmail for me), the “To” field displays the wrong person if you respond only to one person in the conversation.
E.g., Person A sends an e-mail to person B, C, D, E, F. You respond just to Person A. If you then navigate to “Sent”, the “To” field might display person B, instead of person A.
This is confusing, because it makes it look like you sent the e-mail tot he wrong person.