The “I Find This Amoosing” challenge not popping despite dropping the Moose Chandelier in Alexa’s office on her is a bug that several of us are having and have reported in The Bug Report Thread and on Zendesk.
It’s not yet on IOI’s list of Known Issues, but hopefully they will look into it as it seems to be fairly widespread for people who haven’t already unlocked the challenge earlier in H3’s lifecycle and I imagine they are getting several Zendesk tickets reporting the problem.