I followed the advice of one of the respondents above and cleared all instances from my Task list, which included a process from the legacy version. There were a lot of processes, some of which restarted after I ended them. I just kept clicking until they all closed. When I re-started the program, Evernote opened along with an update dialog. Previously, that dialog had opened as a blank box. I just clicked the X because I didn't know what it was. The updated Evernote re-started and is working properly.