Arduino for STM32

No one have encountered problem with the FALLING logic?

I'm not using a mechanical switches, I'm using a second board to generate the signal.
the fact is if i set the RISING logic it work as excepted.

Hello all,
I'm programming a stm32F103C6 with platformio
I'm being mad with this script.
i have setup 2 interrupt pins, one to rise the variable "start" value and one to decrease it.
then the a pwm pin will be set with the "start" value.

The problem rise when I change the logic from RAISING to ...