pin: !fan_part_cooling_pin method for stopping fan spinning at 100% on boot does not seem to work with my setup

[evilC]

What happened

I was following this guide: https://os.ratrig.com/docs/guides/4028/#my-fan-runs-at-100-until-klipper-boots
I tried the following:

[fan]
pin: !fan_part_cooling_pin
cycle_time: 0.00004
enable_pin: PB11

While it stopped the fan from spinning at 100% on boot, I lost speed control of the fan (Any setting > 0% speed yielded 100% speed)

The following did work:

[output_pin 4028_POWER]
pin: PB11
value: 1
shutdown_value: 0 # turn the fan power off on MCU shutdown.

What did you expect to happen

Setting should behave as intended

How to reproduce

Use the supplied entries in printer.cfg

Additional information

RatOS v2.1.x: v2.1.0-RC2-0
100% stock VCore 4-300 set up as per RR documentation (ie fan PWM connected to EBB toolboard, +ve pin connected to Octopus fan pin)
Only deviation from stock is to change fan -ve pin to Octopus heater pin HE3-