Ah, figured it out now. We need to use the new JS_EnterCrossCompartmentCall/JS_LeaveCrossCompartmentCall API around calls using the sandbox object, as it's stored in a different compartment.
Ah, figured it out now. We need to use the new JS_EnterCrossCo mpartmentCall/ JS_LeaveCrossCo mpartmentCall API around calls using the sandbox object, as it's stored in a different compartment.