Hey there 🙂
I think the spot you choose to be the center of the oasis (a watered spot surrounded by 6 desert tiles) needs to also be situated somewhere that can provide enough food. That means the next ring out past the desert has to be high in food. Not sure atm exactly how high but I recall only being able to find two spots on my island where I could put it. I can post a screenshot of my island for you if you want. Spoilers tho, that’s why I’m asking first…
Thanks so much for signing up <3
Hope you’re staying safe, too 🙂