I have Elven Valor, Permafrost, and Savagery old Theme bgs that can't be deleted in the rune manager. In the game client they show up as gold text. However, this makes it so one of my bgs "zzzzz" isn't shown and can't be selected. I've tried renaming it. When I come back from work today I'll try deleting all the other bgs (except the themed decks which I can't X_X) and recreate them.
Make a copy of your battle group, that should allow you to use them. I haven't seen this issue with the theme decks however, I'll try to test it later today.
The problem is I can't delete, rename, or copy them in the rune manager at all X_X. You won't be able to recreate them if you didn't have them before the transfer. Here's a screenshot:
What happens when you click the Edit button? It shouldn't overwrite your older decks. What happens when you make a new deck?
When you click the edit button you get that little black box with the blue outline... no options to rename/delete/copy etc... I did try the copy suggestion and that worked for being able to play the personal bgs again but these theme decks are still locked.
On a different, yet related, topic, I have a number of decks that don't show up as choices to select when starting a match. For example, I have a KF Beast deck that just doesn't show up anywhere. I made an exact copy of the deck and that one shows up. It is odd and frustrating to have to duplicate a deck to play it.
Yes I have that issue to. It may be because we both have the old theme bgs which seem to be indestructable/undeletable