ByRef not working in VBA with value type from a class

Under the hood aClassInstance.publicVariable is encapsulated as a hidden property get/let pair, so passing ByRef is passing the address of the hidden get properties return value, not the underlying variable declared in the class.

You can test this by examining the addresses of the 2 forms of d within the class; they will be different

(class_init)
debug.? " d address=" & VarPtr(d)
debug.? ".d address=" & VarPtr(me.d)