Make sure that the Border option is set to None.
I didn’t really mean that as a workaround, just as a way to verify that Font Awesome is installed correctly. It appears it is, so we can rule that out.
My next suggestion would be to close ALL Panorama windows, quit Panorama, then re-open it, create a new database and new form. Make sure no other windows are open, and the form is in graphics mode. Then open the Font Awesome window and attempt to create a button.
If that still doesn’t work, I’d like to know if you can create objects with the dialogs in the Construct menu. They create form objects the same way as the Font Awesome window does.