Thunderbird with Windows 8.1. Bcc is not working. It says 'undisclosed recipients'then all the e mail addresses are listed too.

The first thing that happened for awhile was that if I sent a message, forward or pictures and used Bcc there was no way to see who I sent something to in my sent folder just 'undisclosed recipients' with no names showing. As of August 4th, if I use Bcc to send a message, forward or pictures, everyone gets the whole list starting with 'undisclosed recipients' and then everyone's e mail address shows up on their e mail. Is there some mail setting that I need to change? Any solutions? Thanks for any help.