jira caches are out of sync

several caches seem to be out of sync.

for one, doing user management (e.g., disabling users) leads to inconsistent results: the filter view may show disabled users as still active. also, user completion in the assign-to combo shows some disabled users (to have the operation fail afterwards).

not sure this is the same underlying problem, but some comments appear to be hidden: take QTBUG-11923. the first comment from duane refers to a comment of mine, which i cannot see in the Comments tab. however, in the All tab, some (strange) traces are visible.