Z-axis home crashes into the bed

I’ve seen this reported elsewhere, but not for my model. Possibly operator error on my part, as it appears to be related to the y-position of the bed. First time it did it, the bed was all the way forward, having just removed a print. Second time it was far enough back that the sensor triggered and it stopped. Not sure what you can do about that without homing the Y axis too, which defeats the object of a z-axis-only home button.

4.0.5 firmware on mainboard and LCD
WanHao i3 Plus Mk2
LCD P/N DMT48270M043_05WT