I'm having a similar issue in a complete vanilla game. It shows the tab with Jasmine Holiday's picture but not the actual quest markers, what to do to complete the quests, and the UI of the event only says she needs help finding out about traditions, but not how this is to be done, and there's no interaction spawning in any conversation category to ask sims about their holiday traditions.
Sorry if this reply goes into wrong place. I don't know how this forum works. I started a new game for the event. All settings are default except some pack specific ones (fame, dust, acne etc. are turned off). No mods installed. I own all expansions except Cat and dogs, almost all packs and some kits.
