I would also be interested in answers to this question. I got the same issue with a newly created place for my village :
https://www.inaturalist.org/places/mesplede-64
I did activate the checkbox for checklist, but the observations previously realised within the territory of the village haven’t automaticaly populate the checklist yet. Maybe there is a delay for this to happen ?
I read there that the checklist can be managed manually. So I begin doing this.
Thanks in advance for any hint.
Florent