Just done some more tests and RTO doesn't engage when I pull thrust to idle on takeoff and engage reverse thrust. Also every single time I land the aircraft bounces off the runway (none of my others do that, it's not my landing!).

Just tried it on a default airport runway (not addon scenery) - again, touchdown descent rate of less than 217fpm and actually the brakes DO engage for a split second but then as the aircraft inevitably bounces, they disarm. Sometimes I don't even see them engage