An example demonstrates:
Internally the Qt5V8 method "toVariant" is called to convert the array to a QVariant. Because this object is actually a custom type (and not a proper V8 Array type) it requires special handling which isn't implemented. Instead an empty QVariant is returned.
This works as expected since the data is moved into a V8 "Array" first, but I'd rather not have to do this for hopefully obvious reasons.