Hello there!
So, I went through buying a LOT of yesteryear bags to see what was in them this year, and I found a couple of bugs along the way.
1. Sometimes you can open a Yesteryear bag from your inventory, the bag vanishes from your inventory, and no box appears with an item in it. The tickets are simply wasted with no 'prize' given for them. This seems to happen every fifteen to twenty bags or so, but the exact time it happens is random. Sometimes this will happen twice or more in a row. I checked to see if it was related to having a large Notifications list, but this is not the case, as I just got the same bug with only one Notification to read three times in a row.
2. Once I opened a Yesteryear bag to find -only- a single Desecrated Grave Soil item in there. No style page was present and I had not yet obtained all of the available pages.
3. I once opened a Yesteryear bag to get a blank bag with absolutely nothing in it.