Hey @Fabrice,
Thanks for reaching out—the behavior you describe actually just seems to be our default styling for events in this way. If you notice, the events that have lower opacity are either in the past, or in the next month.
So in your screenshot, for example, you are viewing the month of February. The events in the bottom that have lower opacity are actually from March, though—the next month over.
Their opacity difference is meant as a way to indicate to users that they are not in the current month, but are instead being pulled in to fill out the calendar grid.
This is a common approach for calendars and you can see it in effect on our official demo site here: http://wpshindig.com/events/.
To override this behavior and keep those events at full-opacity, you can add the following CSS to the bottom of your theme’s style.css file:
.tribe-events-othermonth .tribe-events-month-event-title,
.tribe-events-othermonth div[id*="tribe-events-daynum-"] {
opacity: 1.0 !important;
}
I hope this information helps!
Thanks,
George