Here is the filtered topic posted only in Meta. And I am sure that I open new topics thru email only whenever I visit the forum for the first time in the day.
https://i.imgur.com/HBhpHN3m.jpg
@Little Mouse, do you use email aliasing services like simplelogin? Sometimes, there occurs bounced emails resulting to undelivered messages.
Check out my reply again
If you subscribe for new posts for Meta. So long as you keep posting in the board topics every few days, then you will keep receiving notifications. Once you stop replying like for say over 1 week, the notifications for newly created topics stop coming. Once you post again in the board after the break, the notifications will start coming again
I checked your post history, and you seem to reply topics in Meta after every few days, which is the normal threshold for you to be able to receive more notifications.
That is what I personally observed.