I am having the same problem. I read on another forum that a possible fix could be to Reset Preferences. I have not tried it because it seems like the problem would just come back. I just received a PSE 15 update from Adobe, but it did not fix the problem. List still does not update or change in any way. (PSE15 on Mac 10.11.6 El Capitan)
I just Reset the Preferences, which did not fix the problem.