Thanks, John. I appreciate your input.
I double-checked my Project Settings, General tab and my Primay Output is WebHelp. Under the Index section I have the Index File (HHK) radio button selected, and the Binary Index checkbox is not selected. That is the way it was, in fact, before your posting. So, according to what I have read, those should be the appropriate settings for my simple html webhelp project.
. . . but something has since changed. Just to see what would happen, I manually edited my project HHK file to alphabetize some of the Keywork topics, and then I re-generated the primary layout (WebHelp). The topics that I manually edited now look good, but the other topics that I added since working in RoboHelp 11 are still not listed in alphabetical order in the generated html output--although they are alphabetized in the RoboHelp HTML Editor. Furthermore, now none of the arrows (left, right, up, down) in the editor's Index pod are functional (they appear at the top, but are greyed out). Before only the down arrow and up arrow didn't work. So, I'm still perplexed.
In the meantime, in order to finish the project, I'll just manully work with the HHK file and correct the order of the topics.
Thanks again to everyone for your help.
Peter