[CONNECT C++] Is mdlOutput_rscMessageCenter() broken?

This code fragment attempts to format and print a message loaded from a resource file...

mdlOutput_rscMessageCenter (OutputMessagePriority::Info, 0, MESSAGELIST_Messages,
    MESSAGE_UseTemplateLibrary, MESSAGE_UseTemplateLibrary, OutputMessageAlert::None, libName);

WString	info;
mdlOutput_rscsPrintf (info, 0, MESSAGELIST_Messages, MESSAGE_UseTemplateLibrary, libName);
mdlOutput_messageCenter (OutputMessagePriority::Info, info.c_str (), info.c_str (), OutputMessageAlert::None);

mdlOutput_rscMessageCenter prints this for the brief message of the Message Center:

Using label template library '%s'

And prints this for the detailed message:

Using label template library '\\Asterix\DataDir\Bentley\CONNECT\LA Solutions\Standards\cell\AnnotatorTemplateLibrary.cel'

Why doesn't the brief message get formatted?

The second, more verbose, approach prints this as expected in both the brief and the detailed windows of the Message Center:

Using label template library '\\Asterix\DataDir\Bentley\CONNECT\LA Solutions\Standards\cell\AnnotatorTemplateLibrary.cel'

Have I missed something in mdlOutput_rscMessageCenter?