Same problem for me. The problem seems to have been (temporarily?) solved in the meantime, for I can open chapters again, but the two chapters I tried to open before nonetheless still show "200".
It shouldn't have anything to do with the NA server problem for me since I am in Germany, thus in the middle of Europe. Or do Europeans get connected to the NA server instead of the EU server sometimes?
Switching from "automatic" to EU server really did make the difference. Only, you apparently need to be able to open a chapter to change your reader settings. In the "200" page this was impossible for me to do as it didn't offer this possibility.
Greetings
Albwin