Twisted Pack bugged interaction with Announce Darkness

I use Twisted Pack with Announce Darkness to convert 5 temporary cards in my hand to warlock cards. Typically the cards will stay in hand. Sometimes though, some converted cards will remain temporary. It might be only a specific class of cards (Warrior?) that remains temporary.

Do you have a replay of such a game you could post?

Are they dual-class Warlock/X cards? I assume those would not be replaced by Announce Darkness, because they are not “non-warlock cards”.