The relevant quote from the standard is 5.2.3 [expr.type.conv]/2
The expression T(), where T is a simple-type-specifier or typename-specifier for a non-array complete ob- ject type or the (possibly cv-qualified) void type, creates a prvalue of the specified type,which is value- initialized (8.5; no initialization is done for the void() case). [Note: if T is a non-class type that is cv-qualified, the cv-qualifiers are ignored when determining the type of the resulting prvalue (3.10). —end note ]
The wording in the standard explicitly mentions (in non-normative form) that for non-class types the const-volatile qualification is dropped, but in your case the type is a class, and the note does not apply. It seems that VS is applying the same rule that is applied for non-class types.