closing braces not automatically inserted despite Preference setting (C++)

Did something change in Xcode 9 regarding the “automatically insert closing braces” preference? My checkbox for that option has been set for a long time. After I installed Xcode 9 (now at 9.0.1) the behavior changed in an unexpected way. If I am at “top level” — at the left margin, not inside a brace body — and I type an open brace:

void foo()
{<cursor_here>

then a return, I see:

void foo()
{
   <cursor_here>
}

which is what I expect. But if I am inside a brace body, I do not see the automatic insertion of the close brace:

void foo(bool b)
{
    if (b)
    {<cursor_here>
}

After a return I see:

void foo(bool b)
{
    if (b)
    {
        <cursor_here>
}

with no automatically inserted close brace. While trying this, I noticed that the close brace IS inserted if the open brace is not on its own line:

void foo(bool b)
{
    if (b) {<cursor_here>
}

After typing return:

void foo(bool b)
{
    if (b) {
        <cursor_here>
    }
}

Is there a way to get the pre-Xcode-9 behavior back?