Are there mites or aphids on the underside of the leaves?

No. I don't see any bugs

Hmm... my first thought was mite damage. Not sure, maybe some sort of fungle disorder. My cherimoyas seem pretty bullet proof. I've never had any problems with them at all. Where are you located, maybe that would point at some possibilities.

I'm in Vista. I started care taking for an old cherimoya grove. The soil has been baking in the sun for the last 100 years and is heavily eroded. Ive been spreading compost and using organic liquid fish and kelp.

I can give it more time to hopefully work itself out. Rad. Seems like the best and most natural way to go.