so, i got hit with a pretty bad bug X_X
this past winter veil in 2019, i logged in after the 25th to get my winters veil 2019 Wild Holly and CRashing Thrashing Battleship toys and the FoS associated with them. When i logged in though, i got a message saying that i got the toys and FoS without opening the gifts themselves. the toys eve n appeared in my collection.then i checked my collection/achievements today. I saw that both the FoS and Toys were gone. really dont want to wait til next year to get them again through stolen gift RNG
hopefully blizz support believes me
my achievement pane didnt show the FoS in game today, i definetly remember seeing it and the toys awardewd in my colllection/pane when i logged in around the gift time
worst part is that i didnt take a screenshot or any proof of the FoS showing up, so im not sure this can be fixed X_X
This happened to me as well!
I collected my gifts on the 25th and everything was fine, I even got the ‘Toybox Tycoon’ achievement for collecting 400 toys.
But i logged back in yesterday and both the toys AND the 2019 achievements are gone! But I still have the ‘Toybox Tycoon’ achievement so i know i’m not crazy.
I even still have a few other gifts from the 2019 tree like the Preserved Holly and the Winters Might weapon enchant formula.
Its really frustration to see these things gone 
huh, so its not just me
UPDATE
got a response from Blizzard, sadly they cant restore it, FML
" Hello
I’m Specialist Game Maste and I received your ticket about the Crashin’ Splashin’ achieement and associate Winter Veil gifts.
I completely understand the confusion of logging in to find the toys and Feat of Strength missing, especially after having received the items and being told you already knew them and had the achievement. As I’m sure you’re aware, since the Wild Holly and Battleship weren’t in your Toy Collection, the Feat of Strength does not show as complete. I reviewed the logs of Lightwrath’s activity since before the event started until now to see if we could verify the Wild Holly or Crashin’ Thrashin’ Battleship were looted from either of the 2 Stolen Presents that he opened. The first Stolen Present contained a Graccu’s Mincemeat Pie and a Paper Zepplin Kit and the second contained another Graccu’s Mincemeat Pie and a 5-stack of Zippy Copper Racers. As we were unable to verify the Holly or Battleship, we will not be able to provide a restoration of those items or grant the Feat of Strength to Lightwrath.
I understand that this may not be the answer you were hoping for, but I’d like to thank you for your understanding and, of course, if you need other assistance, don’t hesitate to reach back out to us.
I also am experiencing this issue. I logged into WoW on Dec 28th, looted both toys and learned them, got the FOS. Logged off. Logged back in today, Jan 6th and the toys are gone from my collection and the FOS has disappeared from my achievement list. I’ve submitted a ticket but…we’ll see how that goes…
Hi Again,
I had to speak with two different GM’s to get a clarification on this issue.
The feat of strength and two toys (Wild Holly and Crashin’ Thrashin’ Juggernaut) are not GONE gone from our collections, but “hiding.” There is a bug, or something, that has made them disappear from view, but the GM’s confirmed that they are still there on the back-end, tied to your account.
The second GM I spoke with confirmed that this is a known issue and that supposedly devs are working on a hotfix.
good to know