All, not sure if this was just me but after upgrading my Pi 5B to OS 13.6 my fan stopped working. The fix was to add the following line in /boot/firmware/config.txt. I put it near the top.
dtoverlay=cooling_fan
Thanks for sharing the fix. I’ve seen the Pi 5 fan settings change with the newer cooling configuration, so this is useful to know if the fan suddenly stops after an OS update. It’s also worth checking the current config.txt settings after upgrading, since Raspberry Pi documents the fan configuration under /boot/firmware/config.txt.