Comment 32 for bug 633352

I see very similar logs and symptoms as Mark Abramowitz.

I looked at the code and noticed that first lastAck is created from the event time minus one second. The reminder is triggered instantly.

soapin.js line 346:

function readDismissSnoozeState(aItem, it)
{
 let nextRem = it.t::ExtendedProperty.(t::ExtendedFieldURI.@PropertyId == '34144').t::Value[0];

 if (!nextRem) {
  return;
 }

 nextRem = cal.fromRFC3339(nextRem.toString(), cal.UTC());
 let lastAck = nextRem.clone();
 lastAck.addDuration(cal.createDuration('-PT1S'));

What I observed is that when Thunderbird Lightning is started, it always fetches the calendar event time. Maybe it is the same time than reminder time, I don't know. Anyway, the reminder time is:
"event time minus one second",
no matter how many times the reminder is dismissed and Thunderbird restarted. After dismissing an alert the correct time can be seen in the logs but either it is never saved to server or the wrong parameter is fetched from the server when starting up.