qwerty1111

Why did you use localizes names of days for $dayclass?
Is it allowed to use none Latin characters in CSS class names?

Just proof of concept – I’ve removed ‘$dayclass’ variable from string where calendar cell is formed (line 1502 of my-calendar-output.php) and events became hidden.

I saw this. It’s not it.
Unfortunately I can’t publish site right now. But I did some digging and here are my findings:
this behavior is connected with site language. When language is English events are hidden, but when language switched to Russian all events don’t hide. There are this classes in table cells when english is used: ‘thu future-day has-events author1 mcat_general day-with-date’ (<td id=’mini-2015-12-24′ class=’thu future-day has-events author1 mcat_general day-with-date’>) but for russian language there is only class ‘ day-with-date’ for the very same day.
Another thing on cells for days without events there is classname corresponding to the name of the weekday and that classname is translated. But in russian instead of two letters in unicode it’s written as 4-character string. This is plainly visible on screenshot in my previous post as 4 rombs in a raw in the td-tag classes. This day-class should be first class in the td-tag classes but due to encoding error I guess php interpret it as control characters and weep out following classes up-to last one ‘day-with-date’. Because there is no cells with ‘.has-events’ class no child events are hidden by script.