I have BT issues with my 2014 Mazda 6 GT but I think I figured out the problem for one issue, shuffle.
I like how the car plays music right away because I always have music playing when I drive but it forces my phone to play files in order and not randomly. This annoyed me to no end until I found this site and someone mentioned using the voice command, 'Shuffle All.' I tried and it worked but intermittently. It turns out I just need to wait 1 second before saying the command after pressing the BT button.
One issue I still have which is annoying is when I press the 'pick up' button, it ALWAYS gives me the prompt, "valid command are.." and then it lists 5-6 commands before allowing me to say something. I went to the dealer and the guy there figured out that if you press the 'BT' button after the 'pickup' button, it will shut that b**** up and let you speak. The downside is that I still need to give it 1 second after pressing the BT button in order for it to work properly. Otherwise, the car will just say, "Phone" which isn't what I said.
I love the paddle shifters and the 150ms delay in shifting. Much faster than me trying to change gears on the manual transmission.