set_pwm_period(): PWM load detection is not working correctly

[neuron-whisperer]

I'm developing an application involving a Raspberry Pi 5. I have the Pimoroni I/O expander connected to the I2C GPIO pins, and in general the board is working fine. However, every once in a while, this happens:

>>> ioe.set_pwm_period(60000) Timed out waiting for PWM load!

However, if I invoke that function with wait_for_load=False, the I/O expander behaves just fine, including controlling PWM devices connected to those pins.

Looking at this code:

    def pwm_load(self, pwm_module=0, wait_for_load=True):
        # Load new period and duty registers into buffer
        t_start = time.time()
        self.set_bit(self._regs_pwmcon0[pwm_module], 6)  # Set the "LOAD" bit of PWMCON0
        if wait_for_load:
            while self.pwm_loading(pwm_module):
                time.sleep(0.001)  # Wait for "LOAD" to complete
                if time.time() - t_start >= self._timeout:
                    raise RuntimeError("Timed out waiting for PWM load!")

    def pwm_loading(self, pwm_module=0):
        return self.get_bit(self._regs_pwmcon0[pwm_module], 6)

...it looks like get_bit() is returning 0/False even though the PWM controller has been correctly configured and is behaving as expected.