The vibration motor intensity setting has no effect. Setting it to any value between 0 and 100 does not change the motor at all. The motor is always fully on when it is enabled.

I agree with the comments that the buttons are much more reliable when holding the core2, only touching the white plastic at the same time as a button is enough, no metal parts need to be touched.
Edit: The following was with manually changed uiflow/micropython code btna, b, or c.isPressed()
I also noticed that you can only touch one button at a time, which means some older multi-button apps won't work any more. When you press A (left) and C (right) at the same time, you actually get B (centre)!!

I had exactly the same problem on the outlook app on android.
Luckily I also use the built-in android email app with the same account (i get everything twice), the URL worked immediately, so my email is now verified.

According to a Twitter post from M5Stack they are planning to sell us the same modules as before but in a slightly different form for the core2. Longer bus pins.

Core2 modules

@ajb2k3 Obviously!

@felmue Interesting, I didn't think about taking the battery out of the core2 base holder and leaving it connected.
I've already got a lot of older bases with built-in batteries: Battery bottom, M5Go, Node, Faces I and II. That's why I wanted to disconnect the battery from the core2 core board and instead use the battery power from those bases via the bus.

I changed the Arduino core2 library code and........ it still didn't work?!

Yes, I made sure that the library was really being recompiled correctly!

Still nothing, vibration motor dead?

I just had a random thought, "What if the motor is physically stuck?!".
So I tapped my core2 hard on the table a couple of times, and...... it works!!!

So I actually had a double failure, software and hardware.

By the way, I tried again exactly the same UIFlow/micropython firmware with "Set vibration enable True" and now it works (so there is no problem in the micropython code)..... most of the time.

Unfortunately the motor does seem to get stuck sometimes and needs a tap to get it rotate properly. That's annoying, but it's not dead.

Perhaps the default setting of 2 volts is not really enough to get the motor to always move?

@ajb2k3 M5Stack could have simply supplied a 2x15 bus extender with the core2.
The problem I see is that the micromodule with the mic and IMU will have to be at the bottom of the stack and it won't fit nicely unless you use the core2 base as the bottom. If you don't use it, you've 'lost' two potentially useful sensors for a core2 project which were previously built-in core or base features.
I suppose there might be an idea for different interchangeable micromodules (one at a time) to be used with the core2. That would be neater and more compact than stacking modules, but any wired connections to micromodules would probably be more difficult than modules, units, hats and faces.
I just don't like the fact that older modules can't easily be used with the core2 straight 'out of the box'.

@felmue Thanks! Looking at the code you are right, I'll try overriding it later.

That was obviously VERY well tested code........

I've tried both the core2 arduino library and UIFlow/micropython, but I cannot get the vibration motor to vibrate on my core2.
I know it's connected to pin '3' on the axp192. But I haven't been able to make it vibrate with code like setLDOEnable(3, 1), a short delay and then, setLDOEnable(3, 0).
It seems to be dead.
Turning the power LED off and on with the axp192 works ok.
I've seen one working vibration video demo on the internet but without any code.
I don't know what else to try, are there any working examples for arduino/UIFlow?