Bounty Coins not same as chest description

When I want a certain coin I check the chest. Let’s say I want alextrasza and I play the ice howl bounty.
I win the bounty and don’t get the alextrasza coins. I have the card but I’m not playing with them on my team.
I tried the chest with Jaina coins and got none of them. I don’t own jaina yet.
Is this a bug? Should I own these cards to get the coins in the final chest? And if I own them should they be on my team when I play the chest? I’ve tried 3 times now and no luck, which is annoying on long and more difficult bounties.
I just keep getting junk coins and occasionally one of the coins listed on the chest description.