I'll start with I play on PC and I don't use any mods. I started a new character for the event, a single female living in Willow Creek. I was able to do the event through the planting of the flowers ...
Ideas
Sad to say I had the same thing happen. I told my sim to get mail, read the newsletter, she took it out of her inventory then just stood there. I looked in her inventory and it was no longer there. Nada. No way to progress now. Does anything work as it should - no need to answer.