Just as a point of reference - everyone in this thread who has mentioned not currently getting notifications is a gmail user. Perhaps it is a gmail issue? I know that eons and eons ago - we are talking years and years ago there was an issue with gmail and these types of notifications.
Peter
Very, very, like 99% likely.
Google routinely blocks emails from small or independent providers and does not let the user know in any way. Most times the emails just end up in spam, but commonly they are just dropped with not user notification.
They do this partially out of ignorance /they do not consider independent email servers "trusted" ../ but more as plausible deniability business practice to force customers move to big providers, making independent email servers "unreliable" from the user's perspective.
Little can be done with this except avoiding Google for anything critical. Which is easier said than done these days.