Update:
I actually resolved this myself by modifying lines 62, 112, and 162 of ec_calendar.class.php.
Previously, it had said :
$weekday = ($weekday + 7 – $first_day) % 7;
I simply changed it to say:
$weekday = ($weekday + 8 – $first_day) % 7;
It’s a hack, but it seems to be working properly.
