Does this data explorer query return any topics?
-- [params]
-- group_id :inboxgroup
SELECT tg.topic_id, t.id AS topic_exists, t.deleted_at
FROM topic_allowed_groups tg
LEFT JOIN topics t ON t.id = tg.topic_id
WHERE tg.group_id = :inboxgroup
AND (
t.deleted_at IS NULL
OR t.id IS NULL
)