Air bubble on surface of chocolate
If you're trying to salvage it, I think about all you can do is heat it until it's well melted and let it settle, stirring gently now and then. Hopefully the air bubbles will eventually all come out. I suspect it won't be perfect, and may take a while.

And in the future, just don't use a mixer. Everything should melt and meld just fine with gentle heat and stirring.