Hi Miroslav.
I think your KML file doesn't contains data for infowin, because your setting it is true (do not suppress infowin).
I enabled in my demo joomla.zhuk.cc/index.php/zhgooglemap-mai...eature-kml-elevation
showing infowin and you can see "Трек 5" when click on line.
In your case - empty infowin, but it appears. Check your data.