The Participation Tracker is just blank on the apps sidebar.
Sorry you're having trouble! Are you a host or co-host for this Zoom meeting? Currently the Participation Tracker requires that you be a meeting host or co-host in order to work properly.
As one possible workaround, we have a separate Meeting Timer and Participation App that joins meetings as a Zoom participant. Because of this, it records participation in a different way, so it will work for this even if you are not the meeting host. You can install that app here.