Hi,
In the file, you will find that code
$timestamp = $this->getTimestamp($dateValue);
$phpDate = getdate($timestamp);
if($phpDate['hours'] != 0) {
$timestamp -= $this->timeoffset;
$phpDate = getdate($timestamp);
}
$wday = $phpDate['wday'];
The check for the "hours" is there to handle the issues with the timezone ; because the timestamp is converted into an array in order to extract some information (like the week day).
You can see the add the timeoffset instead
$timestamp += $this->timeoffset;
in order to see if it gave you a better week day. But it is complicated to perform some debug while we are not able to reproduce the issue and get details about the returned data (like the result $phpDate content).
Regards,