I suspect that the fact that you see and empty "Reply-To:" field while composing a new message might be a behavior introduced in one of the more recent versions then mine.
Hopefully, Kostya will shed some light on this behavior soon.
No, the strange behavior is not related to the recent versions, since I'm using build 1.8.2-205 and composing a new message starts with 'collapsed' address header = only the "To" field is shown.
Mikeone,
I believe, the issue (question) is different: In your case, if you click on the icon that reveals "Cc/Bcc" (looks like two heads), - do you see only Cc and Bcc, or also Reply-To ?
In my case (1.6.x), unless I have "Reply-To" configured for a specific address, I see only Cc and Bcc. If Reply-To is configured, then it also shows up with Cc and Bcc.
In case of OP, I believe, even an empty Reply-To shows up when Cc and Bcc are shown.