I found the issue. It's probably due to an update of evernote that did not initialize the value in the menu for the time span displayed.
You can actually see what was wrong in the screenshot included in my original post. At the top right, there is a select menu that is empty and it shouldn't be empty.
This menu HAS to have a value or else the calendar data is not displayed.
But in my evernote, there was no value, even though it shouldn't be possible because there is no "empty" option in the menu :
Once i chose a value in this menu, it solved the issue.
