I have two IronWolf Pro (ST10000NT001) drives. I disabled Idle B (Head Parking) but I'm still occasionally hearing them park and seeing the Load Cycle count increase (approx 1-2 times per 24 hr).

It's obviously not a big deal at this rate, but I'm still curious why it would happen.

- I have verified that the settings have stuck (Idle B Current Timer is always at 0 every time I run --showEPCSettings, even after reboot).
- The load cycles in question are not caused by the PC restarting.
- The Windows "Turn off drives after..." setting is set to Never/0 - the drives are not spinning down.

Is there any reason for occasional head parking even when head parking has been disabled? For example, maybe it's part of some housekeeping routine of the drive?

You need to disable idle_b and idle_b_timer and save that setting. I don't know if and how that works in seatools, but you can do it with sdparm or hdparm in linux.
Another idea would be set the timer to a big number.