I'm having the same issue. I waited for the patch to come out for the helo's and now my wingman won't start up. Which isn't a deal breaker by any means, but I would like a mission complete percentage to be 100. All I can get is 75. I'll try what you have suggested to see if I get them to respond. As of right now all they do is sit there with their lights on. I always start with getting the APU running then set my radios and then I ask for startup clearance. Should I tune my radio first and then start up the APU and then ask for clearance? Also had the same issue where ATC won't answer until I move and then grants taxi clearance and then denies it. Also ATC would grant clearance for take off and then immediately cancel it. Also was told to use the alternate landing site on RTB. It was all weird for me.