Not sure if this helps anybody but so far it has fixed mine. I just traded for my '16 mkc last week and when I got it home I tried to connect my phone then started discovering all the problems. iPhone disconnecting then reconnecting every 5 minutes or so, screen button response very slow, screen seemed to freeze at times, steering wheel volume control would lag, losing gps signal then not reconnecting until a reboot, navigation voice would cut in and out and route would not update very well. I checked and it was on Sync 3.0 which according to the website that's the correct version, maps were NA 1 14. I did a master reset, then disconnected battery for 15 minutes but did not help. I tried leaving my phone off to see if it was causing the problem but that didn't help either.
I read all the articles that pointed to the APIM and I was about to call the Dealer to see if there was a chance they could cover some of the cost since I just bought it 4 days ago. I read that the new APIMs are coming with new map software loaded and wondered if that's where the "fix" is and may not actually be a hardware problem. I decided to purchase the download version of NA 1 19 which is the latest version available right now. It took a couple hours to download and extract to a usb drive then another hour to install in the vehicle. So far this is day 2 and none of the problems are there. The buttons are responsive and the navigation is working good. My phone has not disconnected once.
I'm crossing my fingers that this fixed it because $100 map update is way better than replacing the module.