Chasis Fans Sometimes Don't Spin on Powerup - Unplugging PC/Cycling Power Fixes it

Hi guys,

MSI B850 Gaming Plus Motherboard bought new, this year.
RM850e Corsair PSU (2025 Model) bought new, this year.

4000D Case, 3 Chasis Fans

Sometimes my chasis fans won't spin on a first time powerup of the day. This is fixed by unplugging my PC, I assume draining any residual power and doing a full "power cycle" of the machine. The fans are connected to a 4 pin header, connected to the MB. I've tried them in SYS_FAN 3/4 etc. same outcome.

Is there a BIOS setting I need to change to make this "go away"? All of my headers are firmly connected.

Thanks