FullCalendar with ReactJS: how to keep the original event visible during dragging (like when coping the event with Ctrl pressed)?

Question

I am working on functionality to copy event with keyboard Ctrl key pressed and then drag & drop the event with the mouse. It works pretty good now but I reached to the point where the original event is not visible during dragging which looks strange and must be avoided somehow.

Is there an option or workaround to avoid this disappearing of the original event during dragging? Perfect would be to display the event with some transparency during each dragging.

Here I prepared one sandbox for easier testing:

https://codesandbox.io/s/thirsty-cookies-veh6ow?file=/src/DemoApp.jsx

Please pay attention that in this sandbox, by some reason, you need to keep mouse on focus with the testing area or right. Just click on the text input on top before start testing the functionality in case it is not on focus. Then you must be able to copy each event by dragging it with left mouse key and keyboard Ctrl key pressed down.