Well it's December 29th and the bug is still happening.
I used 2 different toons and completed all New Life quests and also killed
- Northern Elsweyr Dragons x4
- "Old Widow Silk" Spider's Nest, World Boss x2 in Stormhaven
- Leafwater Dolman x3 in Shadow Fen
- Hollow Waste Dolman x1- in Alik'r
- Tarlain Heights Dolman x2 & Pocher Camp World Boss x1- in Grahtwood
And never received the Event tickets x 3 for the boss kills.
It's worked just fine for me up to today.
Also See https://forums.elderscrollsonline.com/en/discussion/505734/extra-event-tickets#latest for others with the same issue.