I've seen a glitch and found what seems to be a solution to the glitch - see if it works for you. Start typing the name of your group and let Mail autocomplete it. Does that give you your group?
The glitch I've seen is that if I make an error in typing a group name which causes me to backspace and retype the group sometimes doesn't expand. I also have a group that had a long name so I created a text expansion to make it more convenient - the expansion works but Mail didn't always recognize it as a group name. I renamed the group.
Yes and thanks. I think I've found the problem... not so much that Mail doesn't work with Groups, it just doesn't behave the same as it did. The email does go through. I had to check it with another email address which was kind of inconvenient. But the recipient did get it.
I used to be able to asure myself that it was a group I was sending the email to by clicking on the down-arrow beside the Group name when you hovered the cursor over the name. That arrow no longer appears, so there's no way of checking to see if it's a valid group address you're using.
But email seems to recognize that it is a valid group...although the sender can't verify it before sending.
Have the same issue. Used to be able to double click on the group name in the address window and that no longer works with Mavericks. As someone pointed out it does work to just type in the group name the click enter.
Hopefully just a glitch that will be corrected but at least there's an easy work around.
Frustratingly having the same problem and very awkward if you want to add two groups in. However seem to have found a workaround.
Go to Contacts and right click on Group you want to load. Click on "Send Email to "Name of Group"" and it will then load all the names into an email. They end up in the "To" box so ready to send. If you don't want to make the names visible to everyone then you have to copy them and post them into "BCC" box and delete from the "To" box.
I hope a fix won't be long in coming.