This project reproduces a fullcalendar regression introduced in the 4.4.0 version.
Run npm install, npm run-script serve and open http://localhost:9000 to start the application.
With version 4.3.1, the left / right arrows contain an icon.
It is a FontAwesome one, manually rendered to SVG. The rendering is triggered by the viewSkeletonRender hook.
When upgrading to the 4.4.0 version (see the 4.4 branch), the icons are rendered the first time but disappear after.