Check to make sure you updated the code fix above in two places. I still see your ical export without some of the "+"'s. Also, there is a problem with the event duration on some of your events. The duration is not at a minute interval, which Google does not like. Try this fix also, which will round the duration to the minute (will be in the next release):
In the file components/com_zcalendar/views/calendar/view.ical.php, at around line 339, change this line:
$duration = (string_zcalendar::toUnixDateTime($row->event_rend) - string_zcalendar::toUnixDateTime($row->event_rstart))/60;
to this line:
$duration = intval((string_zcalendar::toUnixDateTime($row->event_rend) - string_zcalendar::toUnixDateTime($row->event_rstart))/60);