Appear to have messed up party reorganization. Am I missing something?

[The Real Redgar]

So, most recent patch.  Today's "daily gold" is for Seelah to single-handedly complete Undead Uprising.  I have a Story Mode experienced party with all 4 of the "C" deck characters, which has completed AP 0-3, along with other Story Mode parties with all the other characters.  I remove all characters but Seelah from the Party.  They are returned to the "New" section, which I think is a little odd, but it still shows them with all their bonuses, cards, etc.

 

I proceed to complete Undead Uprising with just Seelah: fine and dandy.  I then return to the party selection screen to return the other three characters to the party.  To my dismay, there are no experienced versions saved.

 

Did I do something wrong?  Have I banished my characters into the aether and thereby need to start from scratch again?  Is it possible to return experienced characters to the 'pool', or do characters always need to be in a party to keep their XP?