Deleted contacts from a group still show up in group email address bar, even though they are off of the group contact list. Can’t delete from group.

Even though it looks like I have deleted a contact from a group list,... unchecked the "group" name box and "applied", when I send out an email to the group, the address of who I deleted still shows up on the address bar. I can't get people off of the group even though my group list shows that they are off. All I can do, besides apologizing to unwanted recipients is to completely delete their address from my "all"contact list so they don't exist in my system at all.
This has been happening with the new Outlook program and wasn't a problem with the old one.