I'm not sure when or why or how this turned blue (pictured below), but it seems to be affecting other things that I'm trying to create. For example, it will no longer let me "save and run" my application. Also, it won't let me switch to App Studio anymore. Please let me know if any of you have experienced something similar, and any ideas for how to fix it.
Using 8.1.1, yes, I already tried reloading, logging out and logging back in, changing from author to administrator, shutting pega down and re-opening, and restarting my computer.
Take a look in logs of the same node and see if some exceptions are coming. If you do not see anything in log try delete the whole section rule or part of the section rule without opening in next login.