On my Android phone the expression HERE() was “0.000000, 0.000000”.
Even though in the Android settings I turned on the permission for location for the AppSheet App.
I had to delete all Data in the Android Settings for the AppSheet App (Storage).
After that, HERE() worked again.
I’m using it for a Navi-Action with expression
CONCATENATE("http://maps.google.com/maps?saddr=" , HERE() , "&daddr=" , [Address])