I have the same problem. After completing new quest. I have canceled buff and reapplied. Item says 3rd annual in mementos, however says 2nd in applied buff and character tab. I am also not receiving any event containers after killing bosses. Have tried on multiple characters and I am aware of cool down timer. I’m assuming the two issues are related.

I’m getting xp but not recieving containers. Xp is less important to someone above cp cap. I do events for containers and rewards like the new motifs. Haven’t received first container

You don't get the boxes from killing bosses. You get them from completing daily quests.