Plank not centering properly on external display (laptop)

Linux Mint 21.3 Cinnamon. Laptop with external display. Plank is set to center at the bottom. On the laptop's display, Plank appears properly centered, as intended. On the external display it appears to the right of the screen's center. This is with the external display set to primary. The only way to fix this is to go into Plank settings => Appearance, and toggle the "On Primary Display" option. When toggled, Plank snaps to the center. However, regardless of whether the option is toggled on or off, on reboot Plank will once again be off-center.

What do I do here?