There are many other optimizations built-in to the LispWorks compiler, which affect code generated according to the compiler qualities in effect at compile-time. For example if the compiler was set to inline structure accessors, then tracing structure accessors in code compiled with that setting will produce no output.
While debugging, you could re-compile the code at higher safety or run it interpreted, to obtain the trace output.
LispWorks User Guide and Reference Manual - 21 Dec 2011