2016 Cayenne Base. iPhone 8. Connects every time and use of phone also works. Wife's phone connects just fine as well (iPhone 7). The one thing I don't like is it reverts to the AM/FM tuner each time I start the car. I have to wait a couple of minutes then select my Bluetooth device. Kind of a pain. Our 2015 Ford Edge with Sync remembers the last chosen media source.
Here is my suggestion. If you know someone with another Android phone, pair it and see if it remains paired. If it does then the problem is your phone. If it doesn't then find someone with an iPhone, pair and see if it remains paired. If it doesn't problem is the PCM, if it does then problem is PCM pairing with Androids. From there you'd have two options. See if there is a software upgrade from the dealer that may fix the issue or switch to iPhone. Sadly either choice may cost you about a grand. LOL. Good luck.