Previous version of JMC used to display N/A (Not available or not applicable) for long values equal to Long.MIN_VALUE.

This is no longer the case.

This can for instance be seen in the pause target of the GC Configuration event, now shown as −292 ×10⁶ y, and the updated Park Thread event coming in JDK 12. Double.NaN was also displayed as N/A and I think Integer.MIN_VALUE as well, but I'm not 100% sure.