__NSCFString object not being output in NSLog statement

Question

I have a variable passed to a method using type NSString * that is actually showing up in the debugger:

po [myString class]
__NSCFString

If I po myString from a debugger prompt, I can see the value of the string. However, if I NSLog it, it does not print. From what I understand, NSString and __NSCFString are toll-free bridged, so one can be used like the other. So why is it not printing from an NSLog statement? Is there something I can do to force it?

The string is initialized thus:

NSString *result = [NSString stringWithUTF8String:(const char *)content];

This result variable is passed from one object to another using NSString * arguments. The NSLog statement looks like this:

NSLog(@"Did not find \n%@ %@\n%@",key, name, myString);

Output of this includes the values of key and name but not myString. If I set a breakpoint on the next line, I can query the value of myString using the po command.