Trello – Harvest Plugin Not Showing in Fluid App

I have enabled the "Harvest Time Tracking" plugin in Trello. However, I cannot see the plugin under "Actions" when I view Trello in a Fluid app. (For those who are not familiar, Fluid let's you create a standalone app from a website.)

I've tried to clear the cache in Fluid, both in the app itself as well as using CCleaner, but nothing I've tried allows the "Track Time" option to show up in the Fluid app (I can see this option just fine if I simply browse to trello.com, however).