I too experienced this problem after upgrading to the new 10.2 Windows client. New notes created in the client were fine, but older notes created in the previous version just appeared blank in the content window. I went at least a week, avoiding the new client but checking periodically and the problem did not go away. In the meantime I used the web and my android device a couple of times where I was not experiencing this issue. Suddenly yesterday, the problem seems to have resolved in the new Windows client. I am glad but this experience was a bit disconcerting. Monitoring this thread in hopes that an explanation will be provided.