Guild Wars 2

The Winter Wonderland Mastery resets after you’ve completed it, which renders its status “not achieved.”

Given that it’s a part of the Very Merry Wintersday festival achievement, that means the jp box for that event will forever remain unticked. As someone who’s not very good at ringing bells and throwing snowballs, I find that unfortunate. ;p

That’s not true. They still count. Go back and re-count your achievements under the meta, keeping in mind that Grawnk Munch and Generous Harvest don’t count towards it; your JP/bell/snowball mayhem ones will still be counted (assuming you’d already completed it once).