possible Bug: FVector2D Variable does not get updated on Property.ToSharedRef()->SetOnPropertyValueChanged() in Details Customization

In my detail customization I’m trying to get my delegate called whenever my var is changed. It works with any other datatype except FVector2D. Curiously the delegate gets called when I use the yellow “back to default” arrow next to it.

UPROPERTY(Interp, EditAnywhere, BlueprintReadWrite))
FVector2D MyVar {1.0f, 2.0f};

TSharedPtr<IPropertyHandle> MyVarProperty = DetailBuilder.GetProperty(GET_MEMBER_NAME_CHECKED(AMyClass, MyVar));

MyVarProperty.ToSharedRef()->SetOnPropertyValueChanged(FSimpleDelegate::CreateSP(this, &FMyDetails::MyVarUpdate));

The exact same setup works for dozens of other variables with different types. The same delegate gets also called by a different property of type bool. And again the “back to default” arrow also calls the delegate. Just putting new values in the boxes doesn’t. Any Idea what the reason for that could be besides a bug?