Actually my original answer was incorrect on reading the code.
Try
new ConditionalSleep(random(50_000, 60_000), random(500, 1500)) {
@Override
public boolean condition() throws InterruptedException {
log("Can mine? " + vein.hasAction("Mine"));
return !vein.hasAction("Mine"); // I've tried with and without exclamation, no results.
}
}.sleep();