Our GQs have vanished again, our last was 18th March. ... We lost them last time too, two weeks before the bugfix for:
when players leave a guild whilst a guild quest is active went live, that didn't apply to us then and we are at a loss to determine what's gone wrong this time though the series of events is a perfect repeat of last time. We've been completing them regularly if not every day, we haven't had masses of people joining or leaving and we've not changed anything we've been doing at all so far as we can tell. Even so:
Ages ago:
Waiting Guild Quests disappeared.
Very slightly more recently:
Daily GQs started skipping occasionally and didn't always arrive at the usual time.
19th March:
*poof* GQs vanished entirely.