Insofar as the question does little to describe exactly which macro how and/or why it failed, the only thought that occurs is that macros do not always translate well from one version of NX to the next. In other words if the macro was distributed with an older or newer version of NX than the one you are currently running then it is quite likely that it will not run properly. Otherwise it is relatively unusual that a GM toolkit macro would cause such problems.
Macros are based on menu and dialog appearances. For example Macros can't turn assemblies on, they can only toggle them. Perhaps the reason it is intermittently is because the environment is a little different based on your role or application activation.
Macros should be replaced with journal files for exactly this type of reason. Not everything can be a journal file but most can.
Report it through your GM contact, I don't think GTAC answers those calls anymore.
