Hi @physixfan!
You still can’t track personal messages through the interface (and it’s not on the roadmap) if the users all removed themselves.
However, the bug was fixed and users removing themselves from a PM create small actions posts:
Don’t forget to update Discourse so the fix is applied and install data explorer if you didn’t yet and if you still need to track these actions.
A working SQL query would be:
SELECT user_id, topic_id
FROM posts
WHERE action_code = 'user_left'
ORDER BY id DESC
LIMIT 10