Thanks, RedBarron pointed out that I was actually asking about i-Stop and confusing the two. I didnt think iStop was working as expected. Turns out the non-issue was user error. I was not depressing the brake far enough to activate it.
Yes indeed, the brake has to be quite firmly pressed to allow iStop to activate. And there are a number of other conditions that also have to be met for it to activate. Eg sufficient battery charge, A/C not on max, ambient temp, steering wheel straight, and some others.
And if for some reason you dont want it to activate when the car is stopped, holding the car stopped with light pressure on the brake pedal is the way to do it. You will quickly learn.
I have had CX5’s with iStop since 2014. Never once in that time have I had an issue with it restarting.
Mazda’s implementation of the stop/start system is among the best, if not THE best, of all manufacturers. You may have read that their system cleverly stops the engine at TDC and uses the spark to assist the restarting process, thereby reducing the load on the starting motor.
Some friends with new Mazdas that have never had a stop/start have been worried about how quickly it restarts should they need to make a quick getaway.
I say to them - try this - stop the car so that iStop activates. Now, get someone to say “GO!” and then as fast as you can, take your foot off the brake and onto the accelerator.
I bet that the engine is running and ready to go by the time your foot is pushing the accelerator down. And it always is.
So really, its all a mindset thing and you just need to get used to it.