We have looked into this further and it indeed seems be caused by lag in the internet connection. The newly generated cards are being pushed / pulled from the server when you switch views – this is usually instant but occasionally it may take a little time to update. I have updated the thread title to better reflect this.
Thanks for the report @jawsh. We will make sure to improve this very soon, but in the meantime as @connor mentioned try not to use Thoughts to author cards.