Why does ask.wireshark.org sometimes not send emails?

I have a couple issues with getting email notifications from ask.wireshark.org, and I'm wondering if it's expected behavior or a bug:

1. I usually get emails for tags I've subscribed to (ie, am "interested in"). But if I re-tag someone's question to an interesting tag, it claims to automatically subscribe me but no email notifications are sent when there are updates to the question/comments until I provide an answer.
2. Possible related to (1) above, but if I comment on a question (as opposed to answering it), and then the other user comments as well, I don't get a notification of that either. I.e., either it does not auto-subscribe me for only posting a comment to a question, or else auto-subscribing isn't working for that case either.

(and no, the emails aren't in my spam folder)