Nope. And I just noticed that the same user pinged me again on the 7th; I did not see that either. I do not see either of these pings in the alerts drop-down atm. This has happened with at least one other user, IIRC.
That user's signatures look weird, it doesn't have a link to their user page (and in one case, the timestamp is off by a minute). It may be that it's not being recognized as a signature, or that the user is doing something strange like manually creating a look-alike signature. Mention notifications (annoyingly) are not sent if the user doesn't sign, to avoid sending mentions for things that aren't discussion comments.
Aha! It looks like you get these kinds of signatures if you turn on fancy signatures (the "Treat as wikitext" option in preferences) but don't actually provide a custom signature (the "New signature" field). It looks like there's probably a bug in DiscussionParser that doesn't recognize this as a signature.
Yeah that's right. There's nothing in the signature that makes it particularly recognizable as a signature (to software, at least). I fear this might not be an easy bug to fix, short of fixing how mentions are done generally (see T128535: Consider ping parser function instead of link-based mention, which proposes making mentions use explicit syntax so that we don't have to guess whether you're leaving a discussion comment with a mention or adding a link to a user page while editing a non-discussion page).
Signature have to have at least a link to user page or user talk page to trigger mentions.
Next actions should be:
- update documentation to mention that
- have a fallback on MediaWiki for cases where there is no link in a signature